TeVPA 2018

27 Aug 2018, 07:30 → 31 Aug 2018, 17:25 Europe/Berlin

LVH, Luisenstraße 58, 10117 Berlin

We are pleased to announce that the 2018 TeV Particle Astrophysics conference (TeVPA 2018) will take place in Berlin, Germany. TeVPA is a five day conference which aims to bring together leading scientists in the field to discuss recent advances in Astroparticle Physics.
There is the possibility to host small workshops before and after the conference at DESY in Zeuthen (link, ~50 km south of Berlin). In case of interest in this, please contact us at tevpa2018@desy.de with a brief description of the workshop you would like to organize.

Monday, 27 August

Registration - The conference center is open during the conference.

Opening

Chair: Walter Winter

slides Introduction

1 Opening

Speakers: Christian Stegmann (DESY), Dr Walter Winter (DESY)

Slides 180827_TeVPA_Organization.pptx 180829_TeVPA_Organization_Dinner.pptx

GW and followup

Chair: Walter Winter

2 GW from compact objects and binaries

Follows soon.

Speaker: Brian Metzger (Columbia University)

Slides

• disk.mpg
• rprocess.mp4
• TeVPA18_Metzger.pptx

3 Probing Extreme Gravity and Matter with Gravitational Waves

Follows soon.

Speaker: Alessandra Buonanno (AEI Potsdam)

Slides TeVPA-Buonanno.pdf

4 GW x-ray follow-up

Follows soon.

Speaker: Eleonora Troja (NASA, University of Maryland)

Slides TeVPA18_Troja.pptx

10:30 Coffee Break

Neutrino Astronomy

Chair: Markus Ackermann

5 Recent results in neutrino astronomy

Follows soon.

Speaker: Darren Grant (University of Alberta)

Slides TeVPA2018_NuAstro_DRG.pdf

6 Hunting for neutrino sources with the Fermi-Large Area Telescope

on behalf of the Fermi-LAT coll.

Speaker: Dr Sara Buson (NASA-GSFC)

Slides TeVPA18_final.pdf

7 VHE gamma-ray observations of TXS 0506+056 and perspectives for future follow-up observations

Follows soon.

Speaker: Konstancja Satalecka (DESY)

Slides satalecka_tevpa2018.pdf

8 Radio detection of neutrinos

Follows soon.

Speaker: Anna Nelles (UC Irvine, HU Berlin)

Slides TeVPA_2018.pdf

12:30 Lunch Break

Cosmic Rays: 1

Chair 1: Don Ellison | Chair 2: Denise Boncioli | Chair 3: Andrew Taylor | Chair 4: Daniele Gaggero |
Chair 5: Tony Bell | Chair 6: Markus Ahlers

Conveners: Andrei Bykov (Ioffe Physico-Technical Institute), Dr Sabrina Casanova (IFJ PAN & MPIK HD), Dr denise boncioli (DESY)

9 Measurement of the Proton Flux in Cosmic Rays with the DAMPE Experiment

The Dark Matter Particle Explorer (DAMPE) is a high energy astroparticle satellite launched on the 17th December 2015 into a sun-synchronous orbit at an altitude of 500 km. The DAMPE detector consists of a double layer of Plastic Scintillator strips Detector (PSD), followed by a Silicon-tungsten TracKer-converter (STK), a Bismuth Germanium Oxide electromagnetic calorimeter (BGO) and a NeUtron Detector (NUD). The main scientific objective of DAMPE is to search for possible Dark Matter signatures through detecting electrons and photons in a wide energy range from 5 GeV up to 10 TeV with unprecedentedly high energy resolution. Moreover, the DAMPE satellite will contribute to a better understanding of the origin and propagation mechanisms of high energy cosmic rays via the measurements of fluxes of nuclei up to hundreds of TeV. In this contribution, the latest result of the measurement of the proton component of cosmic-rays is discussed.

Speaker: Ms Stefania Vitillo (University of Geneva)

Slides vitillo_TeVpa2018_DAMPE_protonflux.pdf

10 The expectation of cosmic ray proton and helium energy spectrum measured by LHAASO

Large High Altitude Air Shower Observation (LHAASO), located in Daocheng Haizishan, 4300m a.s.l., Sichuan Province, Chain, is under construction now and is expected to be completely operated by 2021. One of the main science objects of LHAASO is to precisely measure the cosmic rays energy spectrum of individual components from 1014 eV to 1018 eV. LHAASO is consist of four types of detectors: the Water Cherenkov Detector Array (WCDA), the Wide Field-of-View Cherenkov Telescope Array (WFCTA), electromagnetic detector array with an effective area of 1 km2 (KM2A-ED) and Muon detector array (KM2A-MD). In this work, several mass sensitive parameters measured by LHAASO hybrid detection are presented; and primary particle identification is carried out through TMVA analysis. The proton and a mixed proton and helium sample are selected with a purity of 90% and 95% respectively. Furthermore, the expected energy spectrum of light components of CRs is given.

Speaker: Dr Li.Qiao Yin (IHEP, CAS)

Slides The_expectation_of_cosmic_ray_proton_and_helium_energy_spectrum_measured_by_LHAASO.pptx

11 Understanding Very High Energy Cosmic Rays with VERITAS

The origin of very high energy (VHE) cosmic rays is one of the oldest and deepest puzzles of astrophysics. Understanding particle production and acceleration in astrophysical sources, and the mechanisms of propagation of cosmic rays through the interstellar medium is paramount to solving this fundamental problem. Cosmic rays produced in nearby accelerators can be observed directly through measurements of the spectra of cosmic ray electrons, as well as heavy elements, including iron. On the other hand, one of the most powerful ways of studying cosmic rays from singular distant accelerators is the observation of gamma rays that are produced in their interactions with the interstellar medium. Such studies are then most productive focusing on dense energetic regions of space – supernova remnants and starburst cores of nearby galaxies. Imaging atmospheric Cherenkov telescopes (IACTs), such as VERITAS, that detect atmospheric particle showers initiated by VHE cosmic and gamma rays, are uniquely suited for both modes of study. In this talk, we attempt to find clues about the origin of cosmic rays by looking at the VHE gamma ray emission from one of the weakest known extragalactic sources, the starburst galaxy M82, observed with VERITAS and the Fermi Gamma-ray space telescope. We also report on VERITAS studies of the cosmic-ray electron and iron spectra.

Speaker: Mr Andrii Petrashyk (Columbia University)

Slides TeVPA18_CRs_AP_v4_final.pdf

12 The Calorimetric Electron Telescope (CALET) on the International Space Station: Latest results from the first three-years on orbit

The CALorimetric Electron Telescope (CALET) space experiment, which has been developed by Japan in collaboration with Italy and the United States, is a high-energy astroparticle physics mission installed on the International Space Station (ISS). The primary goals of the CALET mission include investigating possible nearby sources of high-energy electrons, studying the details of galactic particle propagation and searching for dark matter signatures. The CALET experiment will measure the flux of cosmic-ray electrons (including positrons) up to 20 TeV, gamma-rays up to 10 TeV and nuclei with Z=1 to 40 up to 1,000 TeV. The instrument consists of two layers of segmented plastic scintillators for the cosmic-ray charge identification (CHD), a 3 radiation length thick tungsten-scintillating fiber imaging calorimeter (IMC) and a 27 radiation length thick lead-tungstate calorimeter (TASC). CALET has sufficient depth, imaging capabilities and excellent energy resolution to allow for a clear separation between hadrons and electrons and between charged particles and gamma rays. The instrument was launched on August 19, 2015 to the ISS with an unmanned carrier HTV-5 and installed on the Japanese Experiment Module-Exposed Facility (JEM-EF). Since the start of operation in mid-October, 2015, a continuous observation has being kept mainly by triggering high energy (>10 GeV) showers without any major interruption. The number of the triggered events over 10 GeV is nearly 20 million per month. By using the data obtained during the first three-years, we will have a summary of the CALET observations: 1) Electron+Positron energy spectrum up to 5 TeV, 2) Proton and Nuclei spectrum up to 100 TeV, 3) Gamma-ray observations, with the performance of observations on orbit. We will present also the results of observations of the electromagnetic counterparts to LIGO-VIRGO gravitational wave events and high-energy counterparts to GRB events measured with the CALET Gamma-ray Burst Monitor (CGBM).

Speaker: Yoichi Asaoka

Slides 180827TeVPA-CALET-asaoka.pdf

13 Multi-wavelength observation of cosmic-ray air-showers with CODALEMA/EXTASIS

Over the years, significant efforts have been devoted to the understanding of the radio emission of extensive air shower (EAS) in the range [20-80] MHz but, despite some studies led until the nineties, the [1-10] MHz band has remained unused for nearly 30 years. At that time it has been measured by some pioneering experiments but also suggested by theoretical calculations that EAS could produce a strong electric field in this band, and that there is possibly a large increase in the amplitude of the radio pulse with lower frequencies. The EXTASIS experiment, located within the radio astronomy observatory of Nançay and supported by the CODALEMA instrument, aims to reinvestigate the [1-10] MHz band, and to study the so-called "Sudden Death" contribution, the expected radiation electric field created by the particles that are stopped upon arrival to the ground. Currently, EXTASIS has confirmed some results obtained by the pioneering experiments, and tends to bring explanations to the other ones, for instance the role of the underlying atmospheric electric field. Moreover, CODALEMA has demonstrated that in the most commonly used frequency band ([20-80] MHz) the electric field profile of EAS can be well sampled, and contains all the information needed for the reconstruction of EAS: an automatic comparison between the SELFAS3 simulations and data has been developed, allowing us to reconstruct in (quasi-)real time the latter ones. At last, the unique capability of the antennas and acquisition system used in CODALEMA widen the observation window up to 250 MHz. The high-frequency electric field (120-250 MHz) at ground level is expected to be distributed following a ring of amplified emission due to Cherenkov-like effects. We see such patterns in the CODALEMA data which, associated to EXTASIS, allows one to study EAS over a very wide band, from 1 to 250 MHz.

Speaker: Mr Antony Escudie (Subatech - IMT Atlantique - Nantes - France)

Slides TeVPA2018_escudie.pdf

14 Radio detection of air showers with LOFAR

Air showers can be detected by the short radio pulses they emit. The LOFAR radio telescope contains a dense core region where 384 antennas are located within a circle of 320 m diameter. Here, the properties of radio emission from air showers have been measured in unprecedented detail. The complicated radiation patterns on the ground have been shown to agree with modern theory, including the full Stokes polarisation. The radio measurements are used to determine the atmospheric depth of the shower maximum with a precision of ~20 g/cm$^2$, allowing for a cosmic-ray mass composition analysis around 10^{17} eV. We present the current status of the experiment and future extensions.

Speaker: Stijn Buitink (Vrije Universiteit Brussel)

Slides 1525_Buitink.pdf

Dark Matter: 1

Chair 1: Louise Oakes | Chair 2: Nathan Kelley-Hoskins | Chair 3: Klaus Eitel | Chair 4: Dan Hooper | Chair 5: Daniele Gaggero | Chair 6: Michele Doro | Chair 7: Mónica Vázquez-Acosta

Conveners: Louise Oakes (Humboldt Universität zu Berlin), Prof. Marc Schumann (Univertity of Freiburg), Dr Miguel Sánchez-Conde (IFT UAM/CSIC)

15 Dark Matter searches with the MAGIC telescopes

Indirect searches for dark matter with the ground-based MAGIC telescopes will be reviewed. Different targets with a large expected dark matter content, such as galaxy clusters and dwarf satellite galaxies, allow to constrain dark-matter annihilation/decay processes up to the TeV mass scale. Latest results from deep observations of the galaxy cluster Perseus and the dwarf spheroidal Ursa Major II will be presented.

Speaker: Dr Monica Vazquez Acosta (Instituto de Astrofisica de Canarias)

Slides DarkMatterSearches_MAGIC_MVazquezAcosta_TeVPA2018_Berlin_27Aug2018.pdf

16 The VERITAS Dark Matter and Astroparticle Physics Program

VERITAS is an imaging atmospheric Cherenkov observatory that is sensitive to gamma rays in the energy range between 85 GeV and > 30 TeV. VERITAS observations allow for the study of a wide variety of physics, including energetic environments inside and outside our galaxy, searches for dark matter, and a number of topics in astroparticle physics. We present an update on indirect dark matter searches performed with VERITAS, describe the current status and future prospects of the VERITAS multimessenger program, and summarize recent astroparticle physics results. Nathan Kelley-Hoskins, for the VERITAS Collaboration

Speaker: Mr Nathan Kelley-Hoskins (DESY)

Slides slides.pdf

17 Indirect Dark Matter Searches with the HAWC Observatory

TeV photons provide unique tests of fundamental physics phenomena, such as dark matter annihilation and decay. The High Altitude Water Cherenkov (HAWC) Observatory is an extensive air shower array sensitive to gamma rays from 500 GeV - 100 TeV. HAWC is capable of performing indirect dark matter searches in a mass range that is inaccessible to most other experiments. The HAWC wide field-of-view enables dark matter searches in hundreds of potential sources across the Northern sky. Here, we present dark matter annihilation and decay limits from dwarf galaxies, the Milky Way Galactic halo, the M31 galaxy, and the Virgo Cluster.

Speaker: Pat Harding (Los Alamos National Laboratory)

Slides TeVPA_Harding.pdf

18 Robust estimate of dark matter distributions in the Galactic dwarf spheroidals

The galactic dwarf spheroidal (dSph) galaxies are the promising targets for the dark matter indirect searches for particle dark matter. To place robust constraints on candidate dark matter particles, understanding the dark matter distribution of these systems is of substantial importance. However, various non-negligible systematic uncertainties complicate the estimate of the J-factors relevant for the dark matter searches in these objects. In particular, the effects of non-sphericity of dark halos and the contamination stars have attracted attention because these are unavoidable uncertainties. In this study, using the current available kinematic data of the Galactic dSphs, we investigate the effects of them on J-factor estimation simultaneously. We construct axisymmetric dynamical models combined with new likelihood analysis which takes spatial and velocity distributions of the member and contamination stars into account. We apply these models to most recent kinematic data for classical and ultra-faint dwarfs and estimate their dark matter distributions and then J-factors. Then we compare our results with previous dynamical analyses based on the assumption of spherical symmetry and conventional elimination methods for contamination. In this talk, we introduce our constructed combined dynamical analysis and show a comparison of J-factor estimations from our analysis and the previous ones. In addition, as an intriguing result, we find that some of dSphs favor cusped dark halo rather than cored one even considering a mass-anisotropy degeneracy.

Speaker: Dr Kohei Hayashi (Institute for Cosmic Ray Research, The University of Tokyo)

Slides TeVPA2018_KH_pptx.pdf

19 Model-independent constraints on dark matter annihilation in dwarf spheroidal galaxies

Dwarf spheroidal galaxies are are exceptionally clean targets for searches for gamma rays from dark matter annihilation. Here, I will discuss a general, model-independent formalism for determining bounds on the production of photons from dark matter annihilation in dwarf spheroidal galaxies. This formalism is applicable to any set of assumptions about dark matter particle physics or astrophysics. As an illustration, I'll present an analysis of gamma-ray data from the Fermi Large Area Telescope, which can be used to derive constraints on a variety of nonstandard dark matter models, several of which have not previously been studied in the context of dwarf galaxy searches.

Speaker: Pearl Sandick (University of Utah)

Slides FermiDwarfsTeVPA2018.pdf

20 Refined Dark Matter Spectra for Cherenkov Telescopes

Cherenkov telescopes such as HESS, VERITAS, and CTA, represent one of the most promising avenues to detect popular dark matter candidates like the wino, higgsino, and minimal dark matter. Yet theoretical predictions for the annihilation rate and spectrum of photons produced in such models is a notoriously difficult multi-scale problem, sensitive to the dark matter mass, electroweak scale, and also the energy resolution of the detector. In this talk I will explain how to overcome these challenges using an effective field theory description. This approach allows for an explicit factorization and consistent treatment of the different scales. Taking the example of wino dark matter, this approach results in a photon spectrum which can deviate noticeably from an exact line, and I will present an estimate of how these variations impact the HESS galactic center dark matter line search.

Speaker: Mr Nicholas Rodd (Massachusetts Institute of Technology)

Slides WinoSpectra-NickRodd.pdf

Galactic Science: 1

Chair: Jacco Vink

Conveners: Mr Dmitry Khangulyan (Rikkyo University), Emma de Ona Wilhelmi (CSIC-IEEC), Dr Luigi Tibaldo (IRAP)

21 Galactic High-Energy Particle Accelerators

Progress in observation and theory allows to study Galactic sources of Cosmic Rays in ever increasing numbers, variety and phenomenological complexity. We are presently witnessing the complement of deep studies of individual sources by population aspects, and Galactic source physics reaching out into the extragalactic domain. Some source classes presently evade generalization owing to uniqueness (Galactic Center), complexity among the class constituents (gamma-ray binaries), or absence of firm identification (e.g. young stellar cluster). I will review properties and phenomenology of Galactic sources in the interplay between observations and concepts of particle acceleration suggested to explain the Galactic high-energy sources.

Speaker: Olaf Reimer (UIBK)

Slides olr_TeVPA_2018.pdf

22 Multi-wavelength studies of interstellar shocks

Shocks of stellar winds and supernova remnants (SNRs) can accelerate particles to energies of 100 TeV or higher and are thus believed to be sources of Galactic cosmic rays. Multi-frequency studies of SNRs and superbubbles from radio to X-rays help to understand the propagation of shock waves and their interaction with the ambient medium, while combining the study of interstellar shocks with that of GeV to TeV sources will improve our knowledge of the physics of interstellar shocks, the nature of the gamma-ray sources, and the origin of Galactic cosmic rays. I will give an overview of the studies of SNRs and superbubbles, present recent results, and discuss the implications for their TeV emission.

Speaker: Manami Sasaki (FAU)

Slides Sasaki.pdf

23 The populations of Pulsar Wind Nebulae and Supernova Remnants observed by H.E.S.S.

The H.E.S.S. Galactic Plane Survey (HGPS) provides the most comprehensive view to date of the inner Milky Way in TeV gamma-rays. Of the sources detected, 40% can be firmly identified, mostly as pulsar wind nebulae (PWNe) or supernova remnants (SNRs). The uniform analysis of the HGPS allows systematic studies of the populations of these two classes of TeV-emitting objects. The population of detected PWNe exhibits a good correlation of TeV gamma-ray surface brightness with pulsar spin-down power, which can be explained by the combination of a weaker trend of decreasing TeV luminosity and increasing extension with age. Large offsets of the PWN center with respect to the pulsar are seen for objects older than about 10 kyr. In addition to the firmly identified PWNe, we find that 10 additional sources are plausible PWN candidates. Several TeV sources identified as SNRs have a shell-type morphology. The HGPS allowed the discovery of three new sources with this morphology, one with a radio counterpart and two SNR candidates. The TeV properties of these SNRs and SNR candidates will be reviewed. A population study including upper limits on undetected SNRs allows conclusions on the particle acceleration efficiency and gamma-ray production in these objects.

Speaker: Dr Yves Gallant (LUPM, CNRS/IN2P3, U. Montpellier)

Slides PWN_SNR_pops_TeVPA_v3.pdf

24 NuSTAR and VERITAS observations of unidentified Galactic HAWC sources

We present follow-up X-ray and gamma-ray observations of two unidentified Galactic HAWC sources, 2HWC J1928+177 and 2HWC J1953+294, with the NuSTAR and VERITAS observatories. VERITAS gamma-ray observations of 2HWC J1928+177 resulted in upper limits, while a follow-up NuSTAR X-ray observation detected a variable X-ray point source with a bright IR counterpart. The HAWC source could be powered by this variable X-ray source (which might indicate a new gamma-ray binary system) or by a nearby radio pulsar, PSR J1928+1746. The second unidentified HAWC source, 2HWC J1953+294, has been associated with an ageing pulsar wind nebula (PWN), DA495. NuSTAR and VERITAS observations of DA495 allow us to study its multi-wavelength SED and determine whether the HAWC source is powered by the PWN. We will also overview our HAWC-VERITAS-NuSTAR observation campaign and present some preliminary results from a few other TeV gamma-ray sources as well as our future plans.

Speaker: Dr Kaya Mori (Columbia University)

Slides KMori_TeVPA2018.pdf

25 HESS J1826-130: an extreme particle accelerator in the Galactic Plane

HESS J1826$-$130 is an unidentified very-high-energy (VHE, E>0.1 TeV) gamma-ray source discovered by H.E.S.S. along the Galactic plane. The analysis of 215-hour H.E.S.S. data has revealed a steady TeV source with an extension of 0.21°. The source spectrum can be well described with a power-law function, showing a very hard spectral index of $\Gamma$ = 1.8 and an exponential cut-off at ~15 TeV. The apparent VHE emission of the source is strongly contaminated by the tails of the bright VHE emission from HESS J1825$-$137. Assuming a hadronic scenario and taking into account the properties of dense gas regions coincident with the best fit position of the source, investigation of the HESS J1826$-$130 spectrum suggests that the astrophysical object producing the observed VHE emission must be capable of accelerating the parental particle population close to PeV (10$^{15}$ eV) energies. In such a scenario this source would be a representative of population of PeV accelerators active in the Galaxy. A leptonic scenario, where electrons accelerated by the pulsar PSR J1826$-$1256 are up-scattering cosmic microwave background or infra-red photons, can also explain the VHE emission. In this case, HESS J1826$-$130 could be an example of a distinctive pulsar wind nebulae population, showing hard spectra and high cut-off energies.

Speaker: Dr Ekrem Oguzhan Angüner (CPPM)

Slides TeVPA-2018_HESS_J1826-130_EO_ANGUNER_ID238.pdf

Neutrino Astronomy: 1

Chair 1: Fabrizio Tavecchio | Chair 2: Andrea Palladino | Chair 3: Francesco Villante | Chair 4: Joshua Wood | Chair 5: Summer Blot | Chair 6: Markus Ahlers

Conveners: Dr Aart Heijboer (NIKHEF), Dr Andrea Palladino (DESY), Claudio Kopper (University of Alberta)

26 Recent results from IceCube

The IceCube Neutrino Observatory studies a wide range of phenomena including neutrino astronomy, dark matter searches, neutrino oscillations, and cosmic ray physics using a cubic kilometer of instrumented ice at the South Pole. Recently, IceCube reported evidence for the first identified source of the high energy astrophysical neutrino flux. This represents a major milestone towards understanding both the sources of high energy neutrinos and cosmic rays but the picture is far from complete. In this talk I will summarize IceCube's recent results and highlight how the identification of a high energy neutrino source fits into the context of IceCube’s broader work to measure and understand the high energy astrophysical neutrino flux.

Speaker: Joshua Wood (University of Wisconsin, Madison)

Slides TeVPA_2018_IceCube_Results.pdf

27 Detection of a flaring blazar coincident with an IceCube high-energy neutrino

On September 22, 2017, the IceCube Neutrino Observatory has observed for the first time ever an extremely high-energy neutrino IceCube-170922 in spatial and temporal coincidence with a gamma-ray flaring blazar, TXS 0506+056, observed with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Following the original IceCube alert, the source has been observed by several telescopes in a broad wavelength band. Most notably the LAT has reported an increase of the source’s gamma-ray flux by a factor of ~6 compared to its average state. Emission of very high-energy gamma rays was then observed by MAGIC. Triggered by these detections, archival IceCube events, as well as multi-messenger data have been analyzed in order to better understand the physics and the time-evolution of the object. In this talk we report on the combined result from all analyses, establishing if the correlation with TXS 0506+056 is a chance coincidence or indication of a neutrino source.

Speaker: Anna Franckowiak (DESY)

Slides TeVPA_2018.pptx

28 Search for Neutrinos from the blazar TXS 0506+056 using 10 years of IceCube data

A high-energy neutrino event detected by IceCube on 22 September 2017 was coincident in direction and time with a gamma-ray flare from the blazar TXS 0506+056. Prompted by this encounter, 10 years of IceCube neutrino data were searched for additional, independent neutrino emission from the position of the blazar. Two methods were applied to search for an excess of neutrino events in the direction of TXS 0506+056: a time-dependent analysis searching for flux variations on time scales ranging from minutes to months, and a time-integrated search over the the entire analysis period. In this contribution, both analyses will be presented along with their results.

Speaker: Dr Imen Al Samarai (UNIGE)

Slides TeVPA_TXS_1.pdf

29 Photo-hadronically produced neutrinos from TXS 0506+05?

Recently, the IceCube Neutrino Observatory has alerted the astrophysical community about the detection of a very energetic neutrino event (called IceCube-170922A). Upon this alert, the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope reported enhanced gamma-ray emission from BL Lac object TXS 0506+05, compatible with the direction of IceCube-170922A. The fact that this blazar was found in an elevated flux state at LAT energies at the time the 2017 neutrino event occured, motivated a possible association between the gamma-ray source and the neutrino event. Using quasi-simultaneous multi-messenger data of TXS 0506+05, we present here generic model constraints for a photo-hadronic origin of the detected neutrino emission.

Speaker: Prof. Markus Boettcher (North-West University)

Slides TeVPA2018_Boettcher.pdf TeVPA2018_Boettcher.pptx

30 Dissecting the region around IceCube-170922A

On September 22, 2017, the IceCube Neutrino Observatory has observed for the first time ever an extremely high-energy neutrino IceCube-170922 spatially and temporally consistent with a  gamma-ray flaring blazar, TXS 0506+056. The region around the event is, however, crowded with several other thermal and non-thermal sources. In order to get a clear picture of the possible neutrino counterparts we have performed a detailed multi-wavelength study of the region including all publicly available astronomical data. As a first step we use radio and x-ray data in order to identify the most interesting non-thermal counterpart candidates. Following we study the behaviour in time and energy for these sources with a special focus on archival Fermi-Lat gamma-ray data. In this talk we present the result of this *dissection* and discuss a possible gamma-ray to neutrino connection for the source candidates.

Speaker: Mr Theo Glauch (Technical University of Munich)

Slides TXS.pdf

31 Interpretation of the coincident neutrino observation and a bright flare from blazar TXS0506+056

On September 22nd 2017, the IceCube Neutrino Observatory reported a muon track from a neutrino with a very good positional accuracy. The alert triggered a number of astronomical follow-up campaigns, and the Fermi gamma-ray telescope found as counterpart an object named TXS0506+056 in a very bright, flaring state; this observation may be the first direct evidence for an extragalactic source of very high-energy cosmic rays. Here we perform a detailed time-dependent modeling of these relevant processes and present a self-consistent model for the source. We find a slow but over-proportional response of the neutrino flux during the flare compared to the production enhancement of energetic cosmic rays. We also demonstrate that energetic cosmic-ray ions, which produce the neutrinos, provide emission in the hard X-ray band and, to a lesser degree, in TeV gamma rays, whereas optical photons and GeV-scale gamma rays are predominantly radiated by electrons. Our results indicate that especially future X-ray and TeV-scale gamma-ray observations of nearby objects can be used to identify more such events.

Speaker: Dr Shan Gao (DESY)

Slides TeVPa18_Shan_Gao_2.pdf

32 Diffuse gamma ray and neutrino produced by AGN winds

Various observations are revealing the widespread occurrence of fast and powerful winds in active galactic nuclei (AGNs) that are distinct from relativistic jets, likely launched from accretion disks and interacting strongly with the gas of their host galaxies. During the interaction, strong shocks are expected to form that can accelerate nonthermal particles to high energies. Such winds have been suggested to be responsible for a large fraction of the observed extragalactic gamma-ray background (EGB) and the diffuse neutrino background, via the decay of neutral and charged pions generated in inelastic pp collisions between protons accelerated by the forward shock and the ambient gas. However, previous studies did not properly account for processes such as adiabatic losses that may reduce the gamma-ray and neutrino fluxes significantly. We evaluate the production of gamma rays and neutrinos by AGN-driven winds in detail by modeling their hydrodynamic and thermal evolution, including the effects of their two-temperature structure. We find that they can only account for less than ∼ 30% of the EGB flux, as otherwise the model would violate the independent upper limit derived from the diffuse isotropic gamma-ray background. If the neutrino spectral index is steep with Γ ≳ 2.2, a severe tension with the isotropic gamma-ray background would arise as long as the winds contribute more than 20% of the IceCube neutrino flux in the 10−100 TeV range. At energies ≳ 100 TeV, we find that the IceCube neutrino flux may still be accountable by AGN-driven winds if the spectral index is as small as Γ∼2.0−2.1.

Speaker: Dr Ruoyu Liu (DESY)

Slides TeVPA18_liuruoyu.pptx

15:42 Coffee Break

15:45 Coffee Break

15:45 Coffee Break

15:50 Coffee Break

Dark Matter: 2

Chair 1: Louise Oakes | Chair 2: Nathan Kelley-Hoskins | Chair 3: Klaus Eitel | Chair 4: Dan Hooper | Chair 5: Daniele Gaggero | Chair 6: Michele Doro | Chair 7: Mónica Vázquez-Acosta

Conveners: Louise Oakes (Humboldt Universität zu Berlin), Prof. Marc Schumann (Univertity of Freiburg), Dr Miguel Sánchez-Conde (IFT UAM/CSIC)

33 Modeling evolution of dark matter substructure and annihilation boost

We study evolution of dark matter substructures, especially how they lose the mass and change density profile after they fall in gravitational potential of larger host halos. We develop an analytical prescription that models the subhalo mass evolution and calibrate it to results of N-body numerical simulations of various scales from very small (Earth size) to large (galaxies to clusters) halos. We then combine the results with halo accretion histories, and calculate the subhalo mass function that is physically motivated down to Earth-mass scales. Our results --- valid for arbitrary host masses and redshifts --- show reasonable agreement with those of numerical simulations at resolved scales. Our analytical model also enables self-consistent calculations of the boost factor of dark matter annhilation, which we find to increase from tens of percent at the smallest (Earth) and intermediate (dwarfs) masses to a factor of several at galaxy size, and to become as large as a factor of ∼10 for the largest halos (clusters) at small redshifts. Our analytical approach can accommodate substructures in the subhalos (sub-subhalos) in a consistent framework, which we find to give up to a factor of a few enhancement to the annihilation boost. Presence of the subhalos enhances the intensity of the isotropic gamma-ray background by a factor of a few, and as the result, the measurement by Fermi Large Area Telescope excludes the annihilation cross section greater than ∼4×10^{-26} cm^{3} s^{−1} for dark matter masses up to ∼200 GeV.

Speaker: Shin'ichiro Ando (University of Amsterdam)

Slides TeVPA2018.pdf

34 Reviving the clumpiness boost for dark matter indirect searches

Cold dark matter candidates generically lead to the structuring of matter on scales much smaller than typical galaxies. This clustering translates into a very population of subhalos in galaxies, which induces an enhancement of the average annihilation rate with respect to a smooth-halo assumption. Recent work by van den Bosch et al. showed that the number of these objects that survive tidal interactions with the galaxy may have been drastically underestimated by numerical simulations. Taking this result into account, we reexamine the impact of clumps on indirect searches for annihilating dark matter, paying particular attention to the gamma-ray and cosmic-ray antiprotons channels.

Speaker: Mr Martin Stref (LUPM)

Slides martin_stref_tevpa2018.mini.pdf

35 Diffuse axion-like particle searches

We propose a new method to search for axion-like particles (ALPs) based on the gamma-rays produced concomitant with high-energy astrophysical neutrinos. The existence of high-energy neutrinos implies production of gamma-rays in the same sources. Photons can convert into ALPs in the sources' magnetic fields, and will travel as ALPs through extragalactic space. Back-conversion in the Milky Way's magnetic field leads to a diffuse anisotropic high-energy photon flux that existing and upcoming gamma-ray detectors, like HAWC, CTA, and LHAASO can detect. This method probes unexplored ALP parameter space, with LHAASO being realistically sensitive to couplings above 10^{−11} GeV^{−1} and masses up to 3×10^{−6} eV in ten years. Our technique also explores viable ALP dark matter parameter space. I am also submitting an abstract to the track Neutrinos on a different topic.

Speaker: Dr Ranjan Laha (Johannes Gutenberg University Mainz)

Slides TeVPA_2018.pdf

36 Study of axion-like particle effects on the transparency of the universe to gamma rays with the Fermi Large Area Telescope

High energy γ-ray photons emitted by astrophysical sources are absorbed by pair production with the diffuse extragalactic background light (EBL), which results in a decrease of the transparency of the universe to γ rays. Multiple extensions of the Standard Model predict the existence of axion-like particles (ALPs), a new type of pseudoscalar particles that can couple to photons in the presence of magnetic fields. Once an ALP is produced, it can travel cosmological distances without being affected by the EBL, leading to a modification of the transparency of the universe to γ rays. If the ALPs oscillate back into gamma rays close to Earth, a boost of the photon flux above a certain critical energy can be expected. In this work we study the opacity of the universe to γ rays with 80 months of data from the Fermi Large Area Telescope. The energy of the highest-energy photon is determined for each γ-ray source in the 2FHL catalog above redshifts z=0.1. By simulating the expected highest-energy photon distributions in the presence and absence of ALPs it is possible to constrain the ALPs parameters for different values of the intergalactic magnetic field strength.

Speaker: Mr Galo Gallardo Romero (DESY)

Slides tevpa18_galo_v4.pdf

37 Light in the Dark -- a Light Dark Matter eXperiment (LDMX)

The origin and observed abundance of Dark Matter can be explained elegantly by the thermal freeze-out mechanism, leading to a preferred mass range for Dark Matter particles in the ~MeV-TeV region. The GeV-TeV mass range is being explored intensively by a variety of experiments searching for Weakly Interacting Massive Particles. The sub-GeV region, however, in which the masses of the building blocks of stable matter lie, is experimentally open territory. This mass range for particles and force carriers occurs naturally in Hidden Sector Dark Matter models. The Light Dark Matter eXperiment (LDMX) is a planned electron-beam fixed-target missing-momentum experiment that has uniquely broad and robust sensitivity to light Dark Matter in the sub-GeV range. This contribution will give an overview of the theoretical motivation, the main experimental challenges and how they are addressed, as well as projected sensitivities in comparison to other experiments.

Speaker: Ruth Poettgen (Lund University)

Slides TeVPA2018_LDMX_RP.pdf

38 Cosmological Constraints on Dark Matter Scattering

There is a substantial effort in the physics community to search for dark matter interactions with the Standard Model of particle physics. Collisions between dark matter particles and baryons exchange heat and momentum in the early Universe, enabling a search for dark matter interactions using cosmological observations in a parameter space that is highly complementary to that of direct detection. Depending on the form of the interaction, scattering is most prominent either at early times or late times. In this talk, I will describe the effects of scattering in the CMB power spectra and show constraints using Planck 2015 data, and I will discuss the implications of late-time scattering during Cosmic Dawn.

Speaker: Dr Kimberly Boddy (Johns Hopkins University)

Slides boddy_tevpa2018.pdf

39 Development of the GAPS Experiment for Cosmic-ray Antideuteron Search

The GAPS experiment is designed to carry out a dark matter search by hunting for low-energy cosmic-ray antideuterons with a novel detection approach. So far not a single cosmic antideuteron has been detected by any experiment, but well-motivated theories beyond the standard model of particle physics contain viable dark matter candidates, which could lead to a significant enhancement of the antideuteron flux due to annihilation of dark matter particles. This flux contribution is calculated to be especially large at low energies, which leads to a high discovery potential for GAPS. The theoretically predicted antideuteron flux resulting from secondary interactions of primary cosmic rays, e.g. protons, with the interstellar medium is very low. GAPS is designed to achieve its goals via a series of ultra-long duration balloon flights at high altitude in Antarctica starting from 2020. The presentation will report on the status of the different GAPS subdetectors as well as on the development of the simulation and analysis tools.

Speaker: Dr Ralph Bird (UCLA)

Slides GAPS_TEVPA.pdf

Extragalactic Science: 1

Chair 1: Tova Yoast-Hull | Chair 2: Günter Sigl | Chair 3: Shigeo Kimura

Conveners: Dr DI MAURO MATTIA (Stanford University), Prof. Guenter Sigl (University of Hamburg), Prof. Kunihito Ioka (Yukawa Institute for Theoretical Physics, Kyoto University), Tova Yoast-Hull (Canadian Institute for Theoretical Astrophysics)

40 Extragalactic cosmic-ray propagation

In the last decades significant progress has been made towards understanding the origin and nature of ultra-high-energy cosmic rays (UHECRs). However, their sources and composition still remain largely unknown. To interpret the data and find the elusive sources of UHECRs, it is important to understand how cosmic rays propagate in the universe. This is not a trivial task, given our limited knowledge of extragalactic background photon fields, cosmic magnetic fields, and photonuclear interactions. In this talk I will explore the challenges of modelling the propagation of cosmic rays and discuss the prospects for UHECR astronomy.

Speaker: Rafael Alves Batista (University of São Paulo)

Slides rafael-TeVPA-18.pdf

41 Studies of the Extragalactic Background Light with the MAGIC telescopes

A measurement of the Extragalactic Background Light (EBL) from a combined likelihood analysis of blazar spectra detected by the MAGIC Telescopes is presented. EBL is the optical-infrared diffuse background light accumulated during the history of the Universe, directly emitted (mostly) by stars or reprocessed by dust, providing unique information about the history of galaxy formation. The low energy photons from EBL interact with very high energy photons from blazars, leaving an energy-dependent imprint on their gamma-ray spectra. The study of the spectra can be used to constrain the EBL density at different wavelengths and its evolution in time. The spectra of 12 blazars in the redshift range z=0.03 to z=0.94, are used to improve previous constraints on EBL by MAGIC. Novel results on the EBL evolution with time will be presented. Combined spectra of Fermi-LAT and MAGIC data are also used to extract wavelength-resolved EBL measurements.

Speaker: Dr Monica Vazquez Acosta (Instituto de Astrofisica de Canarias)

Slides ExtragalacticBackgroundLight_MAGIC_MVazquezAcosta_TeVPA2018_Berlin_27Aug2018.pdf

42 Kinetic modeling of low Mach number collisionless shocks in galaxy clusters

Collisionless shocks are found in a number of astrophysical objects, ranging in size from the Earth's bow shock through solar flares, termination shock of the solar wind, supernova remnant shocks, and merger shocks in galaxy clusters. In the latter case, low Mach number (Ms << 10) shocks are found propagating in a high beta (β > 1) plasmas, where β is the ratio of thermal to magnetic pressure. Observations in X-ray and radio show that cluster shocks are electron accelerators to non-thermal energies. However, the mechanism of particle energization is poorly known. Recent studies with kinetic PIC simulations suggested the so-called shock-drift acceleration followed by particle-wave interactions in the shock upstream as a mechanism of electron injection in high-β regime. However, other works demonstrated the importance of the multi-scale shock structure which includes ion-scale shock-rippling fluctuations that can significantly alter the injection mechanism. Here we present preliminary results of our first-principles 2D large-scale PIC simulations of shocks for conditions of high-β plasmas, as appropriate to galaxy clusters. The aim is to investigate the multi-scale electron injection physics. We demonstrate the slowly growing rippling modes to emerge after a few tens of ion gyro times and their appearance is marked with an increase in accelerated electron energy. This suggests an energization mechanism that is different from processes identified so far in low Mach number shocks. The micro-physics of these processes is now under detailed investigation whose results will be presented at the conference.

Speaker: Dr Jacek Niemiec (Institute of Nuclear Physics Polish Academy of Sciences)

Slides TeVpa2018.pptx

43 Collision dynamics in GRB internal shocks

Due to the large amounts of energy they release, the luminous transients called Gamma-Ray Bursts (GRBs) are of great interest for high energy astroparticle physics. In the fireball internal shock scenario, the prompt high energy emission is generated in collisions between regions of the jet with different Lorentz factors. However, the classical internal shock model faces several difficulties like low overall energy dissipation efficiencies, which could be solved by imposing different assumptions on the collision process. The feasibility of such model modifications can be studied with hydrodynamic simulations. Focusing on the so-called ultraefficient shock scenario, we will discuss the results of these studies and their implications for GRB modeling. Implementing different collision models in multi-collision GRB simulations, we review their impact on the GRB evolution and on the production of multiple astrophysical messengers.

Speaker: Annika Rudolph (DESY)

Slides GRB_collisiondynamics.pdf

44 Super-Eddington accretion onto neutron stars and black holes

Ultra-luminous X-ray sources (ULXs) are extragalactic, off-nucleus, point-like X-ray sources with enormous luminosity $> 10^{39} ~[{\rm erg}~{\rm s}^{-1}]$, which exceeds the Eddington limit for stellar-mass black holes. Because of such a large luminosity, ULXs are expected to be powered by the super-Eddington accretion onto neutron stars or stellar-mass black holes, or sub-Eddington accretion onto intermediate-mass black holes. Recent discoveries of X-ray pulses in some ULXs have confirmed that the super-Eddington accretion onto neutron stars occurs in some ULXs. On the other hand, previous numerical studies showed that common X-ray spectral features of ULXs can be reproduced by the models of super-critically accreting steller-mass black holes. It is very important to reveal differences of the spectral features between super-critically accreting neutron stars and black holes, as well as their dynamics. Here, we present the results comparing dynamics and radiative spectra between super-Eddington accretion flows onto neutron stars and black holes, by performing general relativistic MHD simulations and by post-processing with general relativistic radiative transfer solver.

Speaker: Dr Tomohisa Kawashima (National Astronomical Observatory of Japan)

Slides 1725_Kawashima.pptx

45 Repeating and non-repeating fast radio bursts from binary neutron star mergers

Most fast radio bursts (FRB) do not show evidence of repetition, and such non-repeating FRBs may be produced at the time of a merger of binary neutron stars (BNS), provided that the BNS merger rate is close to the high end of the currently possible range. However, the merger environment is polluted by dynamical ejecta, which may prohibit the radio signal from propagating.We examine this by using a general-relativistic simulation of a BNS merger, and show that the ejecta appears about 1ms after the rotation speed of the merged star becomes the maximum. Therefore there is a time window in which an FRB signal can reach outside, and the short duration of non-repeating FRBs can be explained by screening after ejecta formation. A fraction of BNS mergers may leave a rapidly rotating and stable neutron star, and such objects may be the origin of repeating FRBs like FRB 121102. We show that a merger remnant would appear as a repeating FRB on a time scale of 1–10 yr, and expected properties are consistent with the observations of FRB 121102. We construct an FRB rate evolution model that includes these two populations of repeating and non-repeating FRBs from BNS mergers, and show that the detection rate of repeating FRBs relative to non-repeating ones rapidly increases with improving search sensitivity. This may explain why only the repeating FRB 121102 was discovered by the most sensitive FRB search with Arecibo. Several predictions are made, including the appearance of a repeating FRB 1–10 yr after a BNS merger that is localized by gravitational waves and subsequent electromagnetic radiation.

Speaker: Mr Shotaro Yamasaki (University of Tokyo)

Slides TeVPA18_SY_180827.pdf

Gamma Rays: 1

Chair 1: Stefan Ohm | Chair 2: Ruben Lopez-Coto | Chair 3: Sara Buson | Chair 4: Felicia Krauss | Chair 5: Francesco Longo | Chair 6: David Sanchez | Chair 7: Konstancja Satalecka

Conveners: Dr Ruben Lopez-Coto (INFN Padova), Dr Sara Buson (NASA-GSFC), Mr Stefan Ohm (DESY, Zeuthen)

46 Future space observatories for low energy gamma rays

In recent years several space-based instruments have probed the sky in hard X rays (E∼10–100 keV: NuSTAR, Swift, INTEGRAL) and in gamma rays (E∼0.1-1000 GeV: Fermi-LAT, AGILE) with considerable scientific return. On the other hand, the challenging energy band between these regimes has remained mostly unexplored since COMPTEL on CGRO (1991-2000). I will review the proposals for future space-based MeV gamma-ray observatories and illustrate the scientific expectations that prompted these efforts.

Speaker: Riccardo Rando (University of Padova and INFN)

Slides rando_mevgamma_tevpa18.pdf

47 Development of Next Generation sub-MeV and MeV Gamma-ray Detector

Now we are in the era of multi-messenger astronomy including neutrinos and gravitational waves. However, the observational window for gamma rays between 100 keV to a few tens of MeV is still closed. This energy band can bring a key information on astrophysical phenomena such as the nuclear decaying gamma-ray lines from stellar explosions, e$^-$e$^+$ annihilation line, MeV dark matter and so on. The connection between MeV and GeV/TeV gamma rays is important for the understanding of particle acceleration in gamma-ray emitting objects such as blazars and pulsar wind nebulae. In order to measure sub-MeV and MeV gamma rays, Compton cameras are ideal instruments. With current generation of Compton cameras, we can detect only the energy, position and time of interaction of an incoming photon. The sensitivity of these cameras can be significantly improved by measuring the momentum vector of recoiled electrons. To measure electron trajectories, we developed Si-CMOS hybrid detectors with 20 μm pixel sizes in collaboration with Hamamatsu Photonics. Moreover, we developed a new prototype Compton camera using them, and have demonstrated successfully that measurements of electron momentum vectors improve both the sensitivity of the camera and the signal-to-noise ratio. The resulting angular resolution and energy resolution are 1.75 degrees and the order of 1%, respectively, for 1.3 MeV gamma rays. These achievements will shed light on sub-MeV and MeV gamma-ray astrophysics in the future.

Speaker: Mr Hiroki Yoneda (University of Tokyo)

Slides TeVPA2018_yoneda_upload.pdf

48 AdEPT, the Advanced Energetic Pair Telescope for Medium-Energy Gamma-Ray Polarimetry

We present the Advanced Energetic Pair Telescope (AdEPT) which is being developed as a future NASA/GSFC MIDEX mission to perform high-sensitivity medium-energy (5–200 MeV) astronomy and revolutionary gamma-ray polarization measurements. The enabling technology for AdEPT is a large volume gaseous time projection chamber with high spatial resolution 2-dimentional readout. The accurate 3-dimensional track resolution of the time projection chamber eliminates the need for an anti-coincidence system and calorimeter which simplifies the instrument and significantly reduces the total mass of this mission. AdEPT will achieve high angular resolution (~0.5 deg at 67.5 MeV) and, for the first time, exceptional gamma-ray polarization sensitivity. These capabilities enable a wide range of scientific discovery potential for AdEPT. The key science goals of the AdEPT mission include: 1) Explore fundamental processes of particle acceleration in active astrophysical objects, 2) Reveal the magnetic field configuration of the most energetic accelerators in the Universe, 3) Explore the origins and acceleration of cosmic rays and the Galactic MeV diffuse emission, 4) Search for dark matter in the Galactic center, and 5) Test relativity with polarization measurements. We report on the science goals to be expected from AdEPT and current status of the mission.

Speaker: Dr Andrey Timokhin (NASA/GSFC)

Slides AdEPT-AndreyTimokhin.pdf

49 Towards multi-instrument and reproducible gamma-ray analysis

Analysis and combination of data from different gamma-ray instruments involves the use of collaboration proprietary software and case-by-case methods. By defining a common open format for high-level gamma-ray data (containing event lists and instrument response functions, using the FITS standard) we allow multi-instrument analysis within the context of open-source software. This project aims to perform the first fully-reproducible, multi-instrument very-high-energy gamma-ray analysis. Data of *Fermi*-LAT, MAGIC, H.E.S.S., and FACT, compliant with a preliminary common format (DL3) and analysed with the gammapy science tools, were used to produce a first joint fit of the Crab Nebula spectrum. Aspects of the error evaluation and the release format of a spectral measurement will also be included in the discussion. This talk will promote and review current open data format and science tools to allow VHE gamma-ray astronomy to move towards open reproducible science.

Speaker: Mr Cosimo Nigro (DESY Zeuthen)

Slides joint_crab_TeVPA.pdf

50 Overview of Results from the HAWC Gamma Ray Observatory

The High Altitude Water Cherenkov (HAWC) Gamma-ray Observatory in the high mountains of Mexico was completed in March of 2015 and is now giving us a new view of the TeV sky. HAWC is 15 times more sensitive than the previous generation of wide-field EAS gamma-ray instruments and is able to detect the Crab nebula at 5σ with each daily transit. Unlike Imaging Atmospheric Cherenkov Telescopes (IACTs), HAWC operates 24hrs/day with over a 95% on-time and observes the entire overhead sky (~8sr over the course of the day). This talk will present an overview of recent HAWC results showing our updated sky catalog, our view of the highest energy gamma-ray sky, a summary of recent observation of nearby middle-aged pulsars, as well as performance and plans for operating HAWC with our new outrigger array.

Speaker: Dr Henrike Fleischhack (Michigan Tech)

Slides HAWCoverview_noBackup.pdf

51 The Transient program of the Cherenkov Telescope Array

Fabian Schüssler for the CTA consortium The Cherenkov Telescope Array (CTA) is the next generation high-energy gamma-ray observatory using the Imaging Air Cherenkov Telescope (IACT) technique. It will improve the sensitivity level of current instruments by an order of magnitude, provide energy coverage for photons from 20 GeV to at least 300 TeV to reach to high redshifts and extreme accelerators. It will provide access to the shortest timescale phenomena. CTA is thus a uniquely powerful instrument for the exploration of the violent and variable universe. The ability to probe short timescales at the highest energies should allow CTA to explore the connection between accretion and ejection phenomena surrounding compact objects, study phenomena occurring in relativistic outflows and open up significant phase space for serendipitous discovery. Aiming at playing a central role in the era of multi-messenger astrophysics, the CTA Transient program includes responding to a broad range of multi-wavelength and multi-messenger alerts, including Galactic compact object binary systems as well as gravitational wave detections and high-energy neutrino transients. The most dramatic case is that of gamma-ray bursts (GRBs) where CTA will make high-statistics measurements for the first time above ~10 GeV, probing new spectral components which will shed light on the physical processes at work in these systems. Another key element of the program is rapid feedback to the wider community on the VHE gamma-ray properties of transients. This contribution will introduce and outline the CTA Transients program. It will provide an overview over the various science programs and discuss their links to multi-messenger and multi-wavelengths observations.

Speaker: Dr Fabian Schussler (CEA-Saclay)

Slides CTA-Transients_TeVPA2018_Schussler.pdf

Neutrino Astronomy: 2

Chair 1: Fabrizio Tavecchio | Chair 2: Andrea Palladino | Chair 3: Francesco Villante | Chair 4: Joshua Wood | Chair 5: Summer Blot | Chair 6: Markus Ahlers

Conveners: Dr Aart Heijboer (NIKHEF), Dr Andrea Palladino (DESY), Claudio Kopper (University of Alberta)

52 IceCube Upgrade and Gen2

Since its discovery of the astrophysical neutrino flux, the IceCube Neutrino Observatory has continued to provide invaluable knowledge about both potential neutrino sources and neutrino properties at the GeV-PeV scale through its detection of neutrino interactions via Cherenkov radiation in the deep South Pole ice. In addition, IceCube is a strong partner in the field of multi-messenger astronomy, which involves rapid follow-up of neutrino events with good pointing precision. I will report on the plans for the IceCube-Upgrade, which aims to deploy new optical modules into the deep ice along with improved calibration devices. This Upgrade will greatly improve our understanding of the detector medium, allowing for reduced uncertainties in angular and energy reconstruction, and thereby more precise measurements of neutrino properties, and more precise pointing towards potential astrophysical sources. In addition, the Upgrade will allow for in-situ testing of new optical modules currently under development for the future IceCube-Gen2 detector.

Speaker: Summer Blot (DESY Zeuthen)

Slides ICU&Gen2_SBlot_TeVPA2018.pdf

53 Diffuse neutrino measurements with IceCube high energy starting events

The IceCube neutrino observatory has firmly established the existence of an astrophysical high-energy neutrino component. This discovery was made using the high energy starting events sample (HESE), which uses a veto to significantly reduce atmospheric background. In this talk I will present the latest astrophysical neutrino flux measurement using seven years of HESE. This latest iteration of the analysis has a new extended systematic treatment as well as added statistics. As part of this new characterization, I will report on the compatibility of our observations with detailed isotropic flux models proposed in the literature, measurements of the neutrino cross section, and tests of fundamental space-time symmetries such as Lorentz Violation.

Speaker: Mr Austin Schneider (University of Wisconsin Madison)

Slides Diffuse_Neutrino_Measurements_With_IceCube_High_Energy_Starting_Events.pdf

54 New Measurement of the flavor composition of high-energy neutrino events with contained vertices in IceCube

The IceCube Neutrino Observatory at the South Pole detects Cherenkov light from charged particles produced in neutrino interactions. At the highest energies, the neutrino flux is of cosmic origin, but its astrophysical sources are yet unknown. A measurement of the flavor ratio on Earth can provide important constraints on sources and production mechanisms. In this talk we present the measurement of the flavor composition performed on IceCube's High-Energy Starting Event sample with a livetime of 7 years. We are directly sensitive to each neutrino flavor via the single cascade, track and double cascade event topologies, the latter being the topology produced in tau-neutrino interactions above an energy threshold of ~100 TeV.

Speaker: Juliana Stachurska (DESY Zeuthen)

Slides TeVPA.pdf

55 The blazar TXS 0506+056 associated with a high-energy neutrino: MAGIC VHE observations and multi-messenger implications

In September 2017, the IceCube neutrino observatory revealed an event designated IceCube-170922A with a high probability of being of astrophysical origin. The event was detected in spatial coincidence with the BL Lac object TXS 0506+056 during a period of enhanced GeV gamma-ray activity. We monitored the object in the very-high-energy (VHE; E>100 GeV) band with the MAGIC telescopes, clearly detecting the object. This result marks the first time that VHE gamma rays have been measured from a direction consistent with a neutrino event. In this talk, we interpret MAGIC results on TXS 0506+056 in a multi-wavelength and multi-messenger context and we discuss some implications.

Speaker: Elisa Bernardini (DESY)

Slides talkelisa2.pdf

56 Unresolved blazars as sources of the diffuse astrophysical neutrino flux

The origin of the astrophysical neutrinos detected by IceCube, whose energies extend up to a few PeV, is still unknown. In this work we investigate blazars (a class of relativistic jets from the core of active galaxies) as sources of the diffuse astrophysical neutrino flux. For a blazar of a given luminosity, we calculate the emitted neutrino spectrum using a recently developed numeric radiation model that simulates photo-hadronic interactions of cosmic rays in the jet. We then consider an entire population of sources, taking into account the different evolution of BL Lacs and flat-spectrum radio quasars (FSRQs), two blazar sub-classes. While the cumulative neutrino flux from resolved (catalogued) blazars has already been constrained through stacking analyses, we show that a population of low-luminosity, unresolved blazars (mostly BL Lacs) can dominate the diffuse neutrino flux at sub-PeV energies. On the other hand, in order not to violate the stacking limit, the contribution of resolved blazars (mostly bright FSRQs) must be suppressed, which allows us to place constraints on the baryonic loading of those sources. Our conclusions highlight the importance of future instruments like CTA, which will enable the observation of potential neutrino sources that are too dim or far away for current sensitivities.

Speaker: Mr Xavier Rodrigues (DESY)

Slides tevpa_rodrigues.pdf

57 Calorimetric assessment of a possible association of the high-energy neutrino IC-170922A with the blazar TXS 0506+056

We have previously argued that the probability for the detection of individual neutrinos from individual blazars is expected to scale with the long-term fluence rather than short flares of high gamma-ray flux. Recently, the extremely high energy (EHE) muon neutrino event IceCube-170922A was found to coincide with increased gamma-ray emission from the blazar TXS 0506+056. We use short- and long-term Fermi/LAT gamma-ray and multiwavelength data to obtain a calorimetric assessment of the maximum possible neutrino flux of TXS 0506+056 and a sample of other blazars of similar gamma-ray brightness. We find that an association of the neutrino with a short-term flare of TXS 0506+056 is very unlikely. However, we also find that the long-term fluence of the source accumulated over a long-term outburst since early 2017 is among the highest of all gamma-ray blazars in 2017. From our calorimetric approach, we derive a chance coincidence of the neutrino event IC-170922A with the high-fluence blazar TXS 0506+056, which is independent of other estimates and based on an a-priori-defined method.

Speaker: Mr Michael Kreter (University of Wuerzburg)

Slides TeVPA_2018_kreter_v5.pdf

58 Gamma-ray lightcurve correlation search for IceCube neutrinos from TXS 0506+056 and cumulative search from blazar flares

Blazars are active galactic nuclei which have their relativistic particle jet pointing towards Earth and have been observed to emit gamma rays to very high energies. They are also candidates for the yet-unknown accelerators of ultra-high-energy cosmic rays. In such a scenario, their gamma-ray emission might be associated with neutrinos produced by hadronic interactions in the jet. Correlating the astrophysical neutrinos detected by IceCube, a cubic-kilometre neutrino telescope at the South Pole, with the gamma-ray emission from blazars could therefore reveal the origin of cosmic rays. In our method we focus on periods where blazars show an enhanced gamma-ray flux, as measured by Fermi-LAT, thereby reducing the background of the search. We present results for TXS 0506+056, using nearly 10 years of IceCube data and discuss them in the context of other recent analyses on this source. Further we give an outlook on applying this method in a stacked search for the combined emission from a selection of variable Fermi blazars.

Speaker: Christoph Raab (Université Libre de Bruxelles)

Slides Raab_Lightcurve_17:50_Monday_TeVPA2018.pdf

Reception

Tuesday, 28 August

Cosmic-rays: 1

Chair 1: Kathrin Egberts | Chair 2: Christoph Pfrommer

59 UHECR observations

Follows soon.

Speaker: Carola Dobrigkeit (UNICAMP)

Slides Auger_Dobrigkeit.pdf

60 Towards EeV Astronomy: catching the sources of ultra-high-energy cosmic rays

The violent Universe still defies us, as the sources of ultra-high-energy cosmic rays remain unknown. Yet we have drastically increased the amount of information at very high energies in the last 5 years, with combined observations of cosmic rays, gamma rays, neutrinos, and gravitational waves. We will identify in this talk the multi-messenger data that can be relevant to solve this long-standing mystery, and compare them with the signatures predicted for the most promising source scenarios. For this purpose, we will recall the fate of primary cosmic rays in the source environment and in the intergalactic backgrounds during their flight to the Earth, and estimate their associated astroparticle emissions. We will give theoretical grounds and experimental prospects for successfully launching EeV Astronomy in the next decades. This would likely happen with the collection of hundreds of ultra-high-energy neutrinos, thanks to global multi-messenger networks such as AMON, and with ambitious high-sensitivity high-resolution experiments such as GRAND.

Speaker: Dr Kumiko Kotera (Institut d'Astrophysique de Paris)

Slides 18_08_27_TEVPA_kotera.pdf

61 Particle acceleration in shocks of Radio Galaxies

We discuss the possibility that ultra-high energy cosmic rays (UHECR) may be accelerated by shocks in the lobes of radio galaxies. Acceleration at the termination shocks of jets is problematic because relativistic shocks are poor accelerators to high energy. We show that non-relativistic shocks with suitable Hillas parameters occur in plasma streams flowing out of the jet termination regions and into the lobes. We propose that the radio galaxies Centaurus A and Fornax A were efficient UHECR accelerators during earlier more active phases and that UHECR stored since then in the lobes can account for hotspots in the AUGER data above 57EeV.

Speaker: Prof. Tony Bell (University of Oxford)

Slides TeVPABellTuesday10am.pptx

10:30 Coffee Break

Extragalactic

Chair: Anna Franckowiak

62 AGN jets, particle acceleration and neutrino emission

Follows soon.

Speaker: Dr Kohta Murase (Penn State University)

Slides TeVPA2018.pdf

63 Neutrinos and gamma-rays from extragalactic sources

Follows soon.

Speaker: Markus Ahlers (DESY Theory Group)

Slides Ahlers_TeVPA2018.pdf

64 Recent results from radio observations (Fast radio bursts, MSP’s)

Follows soon.

Speaker: Jason Hessels (University of Amsterdam)

Slides Hessels_TeVPA_Berlin_180828.pdf

Group Picture

12:40 Lunch Break

Cosmic Rays: 2

Chair 1: Don Ellison | Chair 2: Denise Boncioli | Chair 3: Andrew Taylor | Chair 4: Daniele Gaggero |
Chair 5: Tony Bell | Chair 6: Markus Ahlers

Conveners: Andrei Bykov (Ioffe Physico-Technical Institute), Dr Sabrina Casanova (IFJ PAN &amp; MPIK HD), Dr denise boncioli (DESY)

65 Large-scale Anisotropy in the Arrival Directions of Ultra-High Energy Cosmic Rays with the Pierre Auger Observatory

The Pierre Auger Observatory in Argentina is the world's largest observatory for measuring ultra-high energy cosmic rays with an observation area of 3000 km2. The atomic nuclei arriving from outer space reach the highest energies observed in nature. Clues to their origin come from studying the distribution of their arrival directions. We discuss an anisotropy observed at more than the 5 sigma level of significance, which can be described by a dipole signature (Science, Sep 2017, Vol. 357 Iss. 6357, p 1266). We put this observation into the context of searches for cosmic ray origins.

Speaker: Prof. Martin Erdmann (RWTH Aachen University)

Slides TeVPA_Erdmann_20180828.pdf

66 Telescope Array Experiment

Telescope Array (TA) is a cosmic ray detector in the Northern hemisphere that measures cosmic rays of energies from 1 PeV to 100 EeV and higher. TA is a hybrid detector that consists of a ground array of scintillation counters, covering 700 km$^2$ on the ground, and overlooked by the three fluorescence detector stations. Sensitivity of TA has been extended by the TA low energy extension (TALE) to 1 PeV using additional fluorescence telescopes with higher elevation viewing angles together with an infill array. In this presentation, we describe the experiment and show the latest TA and TALE energy spectrum and TA mass composition results. TA anisotropy results will be described in detail a separate presentation.

Speaker: Dr Dmitri Ivanov (University of Utah)

Slides Ivanov_TeVPA_2018_v03.pdf

67 Telescope Array studies of ultra-high-energy cosmic rays: direction-dependent features

Telescope Array observes ultra-high-energy cosmic rays in the Northern hemisphere for 10 years, and the statistics starts to allow for studies of the cosmic-ray flux not only averaged over the field of view, but direction-dependent. I review recent Telescope Array results and future plans related to anisotropy of arrival directions and direction-dependent studies of the energy spectrum and primary composition.

Speaker: Prof. Sergey Troitsky (INR, Moscow)

Slides TA-aniso-TeVPA2018.pdf

68 Cosmic ray spectrum and mass composition from IceTop and IceCube

IceTop is the surface component of the IceCube Observatory at the South pole and consists of ice-cherenkov detector stations at the top of IceCube's strings. The air shower data are analyzed to study the cosmic ray spectrum and composition in the energy range from PeV to EeV. The shower size $S_{125}$ from IceTop alone can be used as a proxy for estimating the primary energy, and unfolded with certain additional assumptions into an all-particle spectrum. In addition, the surface information can be combined with high-energy muon energy loss information for mass separation from the deep IceCube detector for those air showers which pass through both. In a complementary analysis using these coincident events, both the spectrum and mass composition of primary cosmic rays has been extracted using a multivariate analysis. Both of these analyses have been performed on three years of IceTop and IceCube data. The all-particle spectra as well as individual spectra for elemental groups will be presented.

Speaker: Dr Matthias Plum (Marquette University)

Slides tevpa_masscomposition_matthias_plum.pdf

69 AugerPrime: The Pierre Auger Observatory Upgrade.

The Pierre Auger Observatory with its exposure provides us with a large set of excellent data. The analysis of these data has led to major breakthroughs in the last decade, but a coherent interpretation has not yet been achieved. New questions have emerged, including that of the composition of cosmic rays in the energy region of the flux suppression, which is of key importance for making progress. To answer these questions, the Observatory has started a major upgrade, called AugerPrime. The main goal of AugerPrime is to improve the mass composition sensitivity using the surface detectors. At the end of 2016 an Engineering Array of the upgraded detectors has been installed and has taken data since then. In this work, the detectors upgrade will be presented. The expected performance and the improved physics sensitivity of the Observatory will be discussed together with the first data collected with the Engineering Array.

Speaker: Prof. Daniele Martello (INFN Lecce)

Slides AugerPrime_Martello.pdf

70 A next-generation ground array for ultrahigh-energy cosmic rays: Fluorescence detector Array of Single-pixel Telescopes (FAST)

The origin and nature of ultrahigh-energy cosmic rays (UHECRs) are one of the most intriguing mysteries in Astroparticle Physics. The two giant observatories, Telescope Array Experiment and Pierre Auger Observatory, are steadily observing UHECRs in both hemispheres. We highlight their latest results and address the requirements for a next-generation observatory. The Fluorescence detector Array of Single-pixel Telescopes (FAST) is a design concept for the next-generation of UHECR observatories, addressing the requirements for a large-area, low-cost detector suitable for measuring the properties of the highest energy cosmic rays with an unprecedented aperture. We have developed a full-scale prototype consisting of four 200 mm photomultiplier-tubes at the focus of a segmented mirror of 1.6 m in diameter. In October 2016 and September 2017, we installed two full-scale prototypes at the Telescope Array site in central Utah, USA, and began steady data taking. We report on preliminary results of the full-scale FAST prototypes, including measurements of artificial light sources, distant ultraviolet lasers, and UHECRs, and discuss future perspectives.

Speaker: Dr Toshihiro Fujii (Institute for Cosmic Ray Research, University of Tokyo)

Slides 180828_FAST_TeVPA2018_Fujii.pdf

71 Method of cosmic ray investigations in the wide energy range 10^15 – 10^19 eV by means of inclined EAS detection

The new approach to investigations of inclined muon bundles, based on the local muon density spectra (LMDS) phenomenology allows to study primary cosmic rays in a wide energy interval from 10^15 up to 10^19 eV. The features of the proposed method for studying EAS are discussed. The transverse dimensions of EAS rapidly increase with increasing of the zenith angle and, hence, EAS in a wide energy interval can be explored by means of a relatively small coordinate-tracking detector, since in this case possibilities of EAS detection are determined not by array size, but by shower cross section area. In the paper, results of the analysis of the data on inclined muon bundles accumulated from 2002 to 2016 in the NEVOD-DECOR experiment are presented. For the first time, these results demonstrate with more than 3σ significance the existence of the second knee in the EAS muon component spectrum around 10^17 eV of primary energy. An excess of muon bundles at energies about 1 EeV found earlier in DECOR data has been confirmed and analyzed in detail. One of possible explanations of obtained outcomes indicates the appearance of new processes of muon generation. To solve this “muon puzzle”, a long-term experiment on investigation of the energy loss of muon bundles at large zenith angles was started at the experimental complex combining the Cherenkov water calorimeter (2000 m^3) and the coordinate-tracking detector DECOR; the preliminary results are discussed.

Speaker: Prof. Igor Yashin (National Research Nuclear University MEPhI)

Slides TeVPA2018_Yashin.pdf

Cosmology: 1

Chair 1-2: Jakob Nordin

Conveners: Mr Jakob Nordin (HU Berlin), Prof. Jens Jasche (Stockholm University), Dr Jesús Zavala Franco (University of Iceland)

72 Gravitational time delays and the measurement of H_0

Strong gravitational lenses with measured time delays between the multiple images can be used to determine the Hubble constant that sets the expansion rate of the Universe. Measuring the Hubble constant is crucial for inferring properties of dark energy, spatial curvature of the Universe and neutrino physics. I will describe techniques for measuring the Hubble constant from lensing with a realistic account of systematic uncertainties. A program initiated to measure the Hubble constant to <3.5% in precision from strong lenses is in progress. I will show the bright prospects of gravitational lens time delays as an independent and competitive cosmological probe.

Speaker: Prof. Sherry Suyu (Max Planck Institute for Astrophysics / Technische Universität München)

Slides Suyu_TeVPA2018.pdf

73 Improved cosmological constraints from KiDS+VIKING

Gravitational lensing represents a unique tool to study the dark Universe. Small distortions in the images of galaxies caused by the gravitational lensing effect of the matter distribution in the Universe can be detected over the whole sky. Measuring these coherent distortions makes dark matter structures "visible", allows us to study their growth over cosmic time, and yields cosmological insights complementary to other probes like the cosmic microwave background (CMB). Ongoing wide-field imaging surveys exploit this weak gravitational lensing technique to come up with competitive constraints on important cosmological parameters and insights on fundamental physics. In this talk I will first introduce the basic concepts of weak gravitational lensing, review the history and challenges of weak lensing measurements, and then concentrate on recent results from the ongoing European Kilo Degree Survey (KiDS) and VISTA Kilo-degree Infrared Galaxy Public Survey (VIKING) projects. These KiDS/VIKING measurements show some tension with CMB measurements from the Planck mission when the standard cosmological model is assumed. Does this tension represent a first hint at a crack in our tremendously successful standard model of cosmology? Or is our analysis of either of these measurements flawed in some way? Possible solutions to this discrepancy using extensions to the standard model of cosmology, like e.g. evolving forms of dark energy or massive neutrinos, and possible future developments will be discussed. I will conclude with an outlook towards the big experiments of the next decade in this field of research, Euclid and the Large Synoptic Survey Telescope that have the potential to yield some definitive answers to these questions.

Speaker: Hendrik Hildebrandt (Universität Bonn)

Slides 1415_Hildebrandt.pdf

74 How to constrain the properties of self-interacting dark matter using observed dark matter halos?

In this talk, we discuss the relation between the strength of the self-interaction of dark matter (SIDM) particles and the predicted properties of the inner density distributions of dark matter (DM) halos. We present the results of N-body simulations for 28 halos performed for the same initial conditions for cold DM and for SIDM with different cross-sections. We provide a simple phenomenological description of these results and compare with the semi-analytical typically used in the literature. Using these results, we then predict how the inner DM surface density should depend on the SIDM cross-section for observed halos. The observed surface densities of DM halos are known to follow a simple scaling law, ranging from dwarf galaxies to galaxy clusters, with a weak dependence on their virial mass. We demonstrate how this scaling law can be used to place constraints on DM self-interactions using large samples of objects. Such constraints can be more robust than constraints derived from individual objects, especially if one uses kinematic observations to directly constrain the DM mass inside a given radius, rather than fitting the data to a pre-selected profile and then reconstructing the mass.

Speaker: Ms Anastasia Sokolenko (University of Oslo)

Slides sokolenko.pdf

75 A Stringent Limit on Primordial Magnetic Fields from the Cosmic Microwave Backround Radiation

Primordial Magnetic Fields (PMFs), being present before the epoch of cosmic recombination, induce small-scale baryonic density fluctuations. These inhomogeneities lead to an inhomogeneous recombination process which alters the peaks and heights of the large-scale anisotropies of the Cosmic Microwave Background (CMB) radiation. Utilizing numerical compressible MHD calculations based on kinetic consistent schemes, and a Monte Carlo Markov Chain analysis which compares calculated CMB anisotropies with those observed by the WMAP and Planck satellites, we derive limits on the magnitude of putative PMFs. We find that the total remaining present-day field, integrated over all scales, cannot exceed 47 pG for scale-invariant PMFs and 8.9 pG for PMFs with a violet Batchelor spectrum at 95% confidence level. These limits are more than one order of magnitude more stringent than any prior stated limits on PMFs from the CMB which have not accounted for this effect.

Speaker: Dr Andrey Saveliev (Immanuel Kant Baltic Federal University)

Slides Saveliev_Tevpa2018.pdf

76 DarkHistory: A Code for Computing Ionization and Thermal Histories with Dark Matter Energy Injection

Measurements of the CMB and future 21-cm results can set significant constraints on dark matter annihilation or decay. To obtain such limits, a good understanding of how dark matter energy injection affects the ionization and thermal history of the universe is crucial. In this talk, I will present a new and open-source code package called `DarkHistory`, which will compute these histories efficiently and accurately. The code will fully account for both the non-instantaneous nature of energy deposition during the dark ages, and the back-reaction of increased ionization levels on energy deposition into the intergalactic medium, allowing `DarkHistory` to be used at the end of the cosmic dark ages and during the epoch of reionization. Improvements to various cooling and deposition processes such as inverse Compton scattering and photo-excitation will also be discussed.

Speaker: Mr Hongwan Liu (MIT)

Slides 20180828_TeVPA_2018_-_DarkHistory.pdf

77 Is inflation featureless?

Exclusion of several classes of models due to LHC and astroparticle data has revived interest in grand unification. Typical unified theories predict topological defects. We study a particular SUSY SO(10) model which can produce transitory domain walls near grand unification scale, comparable to the scale of onset of low field inflation. While topologically not stable, the D-parity domain walls are indicated to be formed by Kibble mechanism and are referred to as topological pseudo-defects. We study these in the context of inflation and their potential relation to CMB anomalies.

Speaker: Prof. Urjit Yajnik (IIT Bombay)

Slides Yajnik-TeVPA-Berlin-inflationfeatures.pdf

Dark Matter: 3

Chair 1: Louise Oakes | Chair 2: Nathan Kelley-Hoskins | Chair 3: Klaus Eitel | Chair 4: Dan Hooper | Chair 5: Daniele Gaggero | Chair 6: Michele Doro | Chair 7: Mónica Vázquez-Acosta

Conveners: Louise Oakes (Humboldt Universität zu Berlin), Prof. Marc Schumann (Univertity of Freiburg), Dr Miguel Sánchez-Conde (IFT UAM/CSIC)

78 Direct Dark Matter Detection with XENON1T

Observations at cosmological and astronomical scales indicate that the majority of matter in our Universe is in the form of non-relativistic and long-lived dark matter. Its observed relic abundance is consistent with the existence of a neutral, massive particle with little or no self-interaction. A dark matter candidate favoured by extensions of the Standard Model is a Weakly Interacting Massive Particle (WIMP) whose interaction with normal matter can be probed directly via elastic scattering of target nuclei, thus motivating searches through direct detection. XENON1T, a dual-phase time projection chamber using 2-ton liquid xenon as target mass, was constructed in the Laboratori Nazionali del Gran Sasso and is in operation since summer 2016. It aims to observe primarily low-energy nuclear recoils of WIMPs with unprecedented sensitivity. This presentation will cover the design and operation of the detector, as well as the data analysis that led to the currently most sensitive direct dark matter detection experiment in the world.

Speaker: Mr Julien Wulf (University of Zurich)

Slides TeVPA_2018_Julien_Wulf.pdf

79 Dark Matter implications of DAMA/LIBRA-phase2 results

Recently, the DAMA/LIBRA collaboration released updated results from their search for the annual modulation signal from Dark Matter scattering in the detector. Besides approximately doubling the exposure of the DAMA/LIBRA data set, the updated photomultiplier tubes of the experiment allow to lower the recoil energy threshold to 1 keV electron equivalent from the previous threshold of 2 keV electron equivalent. I will discuss the compatibility of the observed modulation signal with Dark Matter scattering. Due to a conspiracy of multiple effects, the new data at low recoil energies is very powerful for testing the Dark Matter hypothesis. In particular, canonical (isospin-conserving) spin-independent Dark Matter-nucleon interactions do not longer allow for a good fit to the DAMA/LIBRA data.

Speaker: Sebastian Baum (OKC &amp; Stockholm University)

Slides Baum_TeVPA.pdf

80 Direct search for light dark matter with the CRESST-III experiment

The CRESST-III (Cryogenic Rare Event Search with Superconducting Thermometers) experiment, located in the Gran Sasso underground laboratory (LNGS, Italy), aims at the direct detection of dark matter (DM) particles. Scintillating CaWO$_4$ crystals operated as cryogenic detectors at mK temperatures are used as target material for elastic DM-nucleus scattering. The simultaneous measurement of the phonon signal from the CaWO$_4$ crystal and the emitted scintillation light in a separate cryogenic light detector provides particle discrimination on an event-by-event basis. This technology is particularly sensitive to small energy deposits induced by light dark matter particles, allowing the experiment to probe the low-mass region of the parameter space for spin-independent DM-nucleus scattering with high sensitivity. In early 2018 CRESST-III completed an initial data taking campaign reaching nuclear recoil thresholds of well below 100 eV. This unprecedented low threshold provides a significant boost in sensitivity beyond CRESST-II which achieved a threshold of 0.3 keV allowing for the first time to probe dark matter masses as low as 500 MeV/c$^2$. New results of CRESST-III will be presented accompanied by a brief status update on the ongoing CRESST-III measurement campaign started in May 2018.

Speaker: Paolo Gorla (Laboratori Nazionali del Gran Sasso - INFN)

Slides TeVPA_CRESST_Gorla.pdf

81 Probing the correlation between stellar and dark matter velocity distributions

A precise knowledge of the local dark matter velocity distribution and its uncertainties is necessary for the correct interpretation of dark matter direct detection data. High resolution hydrodynamical simulations of galaxy formation provide important information on the properties of the dark matter halo, and find that baryons generally make the local dark matter velocity distribution of Milky Way-like galaxies more Maxwellian. I will discuss the correlations between the dark matter and stellar velocity distributions of Milky Way-like galaxies extracted from state-of-the-art high resolution simulations. In particular, I will discuss if there is a subset of stars which trace the dark matter distribution in various simulated Milky Way-like galaxies.

Speaker: Nassim Bozorgnia (Durham University)

Slides Bozorgnia-TeVPA.pdf

82 DANAE - a new experiment for direct dark matter detection with DEPFET silicon detectors

The sub-GeV mass region of the dark matter is foreseeably to be explored intensively in the next generation of direct detection experiments. Essig and others [1] recently discussed the feasibility of detecting the dark-matter electron recoil using low-noise semiconductor detectors as the active target. With a readout noise level below one electron RMS, the sensitivity allows us to test several theoretical models that account for dark matters with sub-GeV mass. One of the two silicon-based architectures that are capable of reaching such noise level is the DEPFET with Repetitive Non Destructive Readout (RNDR). The prototype of this detector has been developed by the Semiconductor Laboratory of the Max Planck Society, and the readout of a single pixel has successfully reached the expected sub-electron noise level as reported in [2]. In this presentation, we will introduce the working concept of the DEPFET-RNDR. Then we will present the new project of DANAE under preparation that plans to apply this type of detector to the direct detection of dark-matter electron recoil. [1] R. Essig, et al., J High Energ. Phys. 2016, 46(2016). [2] A. Ba ̈hr, H. Kluck, J. Ninkovic, J. Schieck, and J. Treis, Eur. Phys. J. C 77, 905(2017).

Speaker: Prof. Jochen Schieck (HEPHY OeAW)

Slides Schieck_DANE_TeVPA.pdf

83 Consequences of a XENONnT/LZ signal for the LHC and thermal dark matter production

The discovery of dark matter (DM) at XENONnT or LZ would place constraints on DM particle mass and coupling constants. It is interesting to ask when these constraints can be compatible with thermal production of DM. We address this question within the most general set of renormalizable models that preserve Lorentz and gauge symmetry, and that extend the standard model by one DM candidate of mass $m_{DM}$ and one particle of mass $M_{med}$ mediating DM-quark interactions. We find that for most of the models considered here, O(100) signal events at XENONnT/LZ and the DM thermal production are only compatible for resonant DM annihilations. Furthermore, we develop a method to forecast the outcome of the LHC Run 3 based on the same hypothetical detection of O(100) signal events at XENONnT. Applying our analysis to simulated data, we find that at the end of the LHC Run 3 only two mutually exclusive scenarios would be compatible with the detection of O(100) signal events at XENONnT, depending on the detection or lack of detection of a monojet signal. This would significantly narrow the range of possible dark matter–nucleon interactions. Finally, we want to give outlook on how this analysis can also be extended to inlcude dijet-searches for the mediator particle at the LHC.

Speaker: Martin Krauss (Chalmers University of Technology)

Slides presentation.pdf

Gamma Rays: 2

Chair 1: Stefan Ohm | Chair 2: Ruben Lopez-Coto | Chair 3: Sara Buson | Chair 4: Felicia Krauss | Chair 5: Francesco Longo | Chair 6: David Sanchez | Chair 7: Konstancja Satalecka

Conveners: Dr Ruben Lopez-Coto (INFN Padova), Dr Sara Buson (NASA-GSFC), Mr Stefan Ohm (DESY, Zeuthen)

84 Fermi LAT observation of the Sun

The Fermi Large Area Telescope (LAT) has provided the largest sample of solar flares with emission greater than 30 MeV to date. These include the detection of the prompt and the delayed emission, in some cases extending up to ~20 hrs. The LAT detected in gamma-rays also three flares placed behind the limb of the visible part of the Sun. These detections are shedding light on the particle acceleration and emission by the active Sun. LAT observed the Sun also in its quiescent state. The high energy gamma-ray emission from the Sun is due to the interactions of cosmic ray (CR) protons and electrons with matter and photons in the solar environment. The observation of the solar emission components may give useful information about the evolution of the solar cycle by probing two different CR components (proton and electrons) in regions not directly accessible by direct observations. In the talk we will present the main results about the Quiet and Active Sun obtained by the LAT in its 10 years of operation.

Speaker: Francesco Longo

Slides TeVPA2018_SunFermi_v3.pdf

85 The many surprises from high-energy gamma-ray observations from the Sun

I will discuss recent results on gamma-ray observations of the Sun with Fermi, which revealed many interesting and surprising features. These gamma rays are expected to be produced by hadronic interactions between cosmic rays and the solar atmosphere. The high flux of gamma rays observed from the Sun requires a large boost of gamma-ray production by some mechanism, which is likely related to solar magnetic fields. Our new results include the first resolved image of the Sun and a mysterious dip in the spectrum between 30-50 GeV. In particular, we also find that the solar gamma-ray spectrum during solar minimum is hard (~$E^{-2.1}$) and reaches at least 200 GeV. This suggests that ground based experiments like HAWC and LHAASO will be important for probing the Sun at TeV regime. Understanding solar gamma rays is crucial for predicting the solar atmospheric neutrino flux, which can realistically be detected by IceCube/KM3NeT, and is important for solar dark matter searches.

Speaker: Dr Ng Kenny Chun Yu (Weizmann Institute of Science)

Slides kcyn_solargamma_tevpa2018.pdf

86 The Colliding Wind Binary Eta Carinae as seen with the H.E.S.S. telescopes

Eta Car is a colliding-wind binary composed of a massive luminous blue variable (~100 solar masses) and a companion star of O or B-type (~ 30 solar masses). Its orbit is very eccentric and has a period of 2023 days. Although the binary has a rich observational history in, e.g. the optical regime, strong experimental evidence for gamma-ray emission from the system has built up only recently. It is now the only colliding-wind binary showing emission in very-high energy gamma rays. Following its detection in high-energy gamma-rays by the Fermi-LAT in 2009, it was detected with 11 sigma in 30 h of observation with H.E.S.S. last year. The detection was made possible due to the addition of a fifth telescope with a 28 m diameter dish to the existing four telescopes in 2012. Here we present the results of the data analysis and discuss them in the context of current models.

Speaker: Eva Leser (Universität Potsdam/ DESY, D-15738 Zeuthen, Germany)

Slides TeVPA_EC_EL_final.pdf

87 Hadronic acceleration and obscuration in $\eta$ Carinae at TeV energies

The $\eta$ Carinae binary system hosts one of the most massive stars and has the highest known mass-loss rate. This dense wind encounters the much faster wind expelled by the stellar companion, dissipating mechanical energy in the shock. In these regions, particles are accelerated to very-high-energies via diffusive shock acceleration and subsequently cooled via inverse-Compton and photo-pion production, emitting $\gamma$-rays already detected by the Fermi-LAT satellite. The low-energy spectrum cuts off at $≲ 10~$GeV and can be explained with a pure leptonic or mixed lepto-hadronic model. The presence of a second component, clearly visible around periastron 2009, can likely be explained via hadronic photo-production. Particle-in-cell hydrodynamic simulations predict a proton spectra variability along the orbit, with a cut off of few $100$ TeV at periastron and few TeV at apastron. The intrinsic $\pi_0$ decay spectrum is a complex convolution of the maximum energy, luminosity, particle drift and obscuration. The out going TeV photons interact with the huge pool of anisotropic UV photons, emitted by the two luminous stars, creating $e^+-e^-$ pairs. This effect is maximized at periastron, due to the higher particle density and the higher intrinsic cut off, and it heavily modifies the observed $\gamma$-ray spectrum. Quick variations of the optical depth are expected due to the moving shape and position of the shock with respect to the two stars along the orbit, and the changing density structure of the gas along the line of sight. The predicted $\gamma$-ray spectrum is consistent with the recent HESS detection. Thanks to its deep sensitivity, CTA could monitor the high-energy flux variations starting from $>30$ GeV with an unprecedented resolution of few days. Furthermore, the wide energy range that CTA can probe could help to disentangle the intrinsic high-energy cut off of the $\pi_0$ spectrum from the $\gamma-\gamma$ absorption, expected to play an important role at lower energies, providing unique additional constrains on the model parameters, geometry and magnetic field configuration, that will help unveil the nature of the high-energy component and its acceleration mechanism.

Speaker: Mr Matteo Balbo (ISDC, Univeristé de Genève)

Slides 1450__Balbo.pdf

88 3D MHD simulations of particle acceleration in Gamma Velorum, Eta Carinae, WR 147, and HD 93129A

In the light of new data regarding the high-energy $\gamma$-ray emission of suspected massive star colliding-wind binary systems, magneto-hydrodynamic simulations can now be refined and adapted in order to provide explanation of past and prediction of future emission characteristics of these sources. We use three-dimensional magneto-hydrodynamic modeling to investigate the structure and conditions of the wind-collision region (WCR) of colliding-wind binary systems including the important effect of radiative braking in the stellar winds. A transport equation is then solved throughout the computational domain to study the propagation of relativistic electrons and protons with energies up to the GeV and TeV range. The resulting distributions of particles are subsequently used to compute nonthermal photon emission components. Relying on a choice of physical parameters (as diffusion coefficient normalization and particle injection rate) that has been inspired by the recent modeling of $\gamma^2$Velorum (WR 11), we make use of known stellar and stellar wind parameters to simulate the non-thermal photon emission of the systems of $\eta$ Carinae, WR 147, and HD 93129A. From the simulated spectra, we make predictions on their future detectability or - if already detected - about their variability pattern in high-energy $\gamma$-rays.

Speaker: Dr Klaus Reitberger (Zentrum für Astronomie,Universität Heidelberg AND Institut für Astro- und Teilchenphysik, Universität Innsbruck)

Slides 1505_Reitberger.pptx

89 Observation of TeV Gamma Rays from the Jet Interaction Regions of SS 433 with HAWC

Astrophysical sources of high-energy radiation such as AGN and microquasars produce relativistic jets. Particle acceleration in jets is theoretically well-motivated, but direct evidence of acceleration in jets has not been observed above a few TeV. Using 33 months of data from HAWC, we present evidence for the production of gamma rays >10 TeV in the jets of SS 433, one of the most powerful microquasars in the galaxy. The very high-energy gamma rays imply the presence of a population of charged particles with energies extending to hundreds of TeV, and possibly to PeV. The gamma-ray measurements also allow us to address several open questions about this system, such as the composition of the jets, the origin of the high-energy radiation, and the strength of the magnetic field.

Speaker: Mr Chang Dong Rho (University of Rochester)

Slides tevpa2018-ss433-changdongrho.pdf

Poster Session and Coffee Break

90 A Catalog Pipeline for Sources in the CTA Galactic Plane Survey

The upcoming Cherenkov Telescope Array (CTA) will provide a significant improvement in both sensitivity and angular resolution compared to current generation imaging atmospheric Cherenkov telescopes. A key science goal of CTA is a survey of the entire Galactic plane. Outcomes of this survey include a census of Galactic gamma-ray source populations (SNR, PWNe, binaries, etc...), identifying possible PeVatron candidates, characterizing the diffuse Galactic gamma-ray emission and improving our knowledge of the origin of cosmic rays. However, in order to exploit the data for these purposes, an understanding of the underlying sources present in the survey data will be necessary. The Galactic plane survey presents many challenges including disentangling sources from underlying diffuse emission from galactic cosmic-rays and source confusion. This talk will describe current efforts to develop a pipeline for cataloging sources in CTA data built with the ctools analysis software. Specific focus will be given to the algorithms used for source detection and characterization in the anticipated CTA Galactic plane survey

Speaker: Joshua Cardenzana (Institut de Recherche en Astrophysique et Planétologie)

91 A Dark Matter Detector Based on the Simultaneous Measurement of Phonons at low temperature.

S. TALBAOUI, H. GRIMECH, E. BAQLOUL, M.HABBAD Laboratory of Materials Physics, Faculty of Sciences and Technologies, Sultan Moulay Slimane University, Beni Mellal, Morocco Abstract One of the most important issues in astrophysics and cosmology is understanding the nature of dark matter. One possibility is that it is made of weakly interacting subatomic particles created in the big bang, such as the lightest particle in supersymmetry models. These particles should scatter elastically of nuclei in a detector on earth at a rate of ~events/kg/week, and will deposit energies of a few keV. Current attempts to detect these interactions are limited by a radioactive background of photons and beta particles which scatter on electrons.Currently a novel particle detector have developed to look for dark matter based on the simultaneous measurement of ionization and phonons in some grammes of crystal of high purity germanium or silicon or diamond at a low temperature. Background events can be distinguished by this detector because they produce more ionization per unit phonon energy than dark matter interactions. The phonon energy is measured as a temperature change in the detector by means of neutron transmutation doped germanium thermistors attached to the crystal.For this reason we studied behavours of these dielectrics and comparing their dispersion relation. In this paper we present a theoretical study based on the vibrational properties of crystal lattices; such as diamond, silicon and germanium. A detailed calculation has been made to determine the dynamic matrices of these lattices. The phonon dispersion curves presented in this work concern the acoustic and optical modes propagating in the ΓX, ΓK and ΓL directions of the Brillouin zone (3D). In order to determine these dispersion curves we used the Born-von Karman model with the approximation of the central forces between the first and second neighbors. The radial and angular force constants were determined by fitting on experimental data using the generalised least squares method. This approach allows to determine the interaction parameters and the vibrational properties for each of the materials studied. Keywords : phonons, force constants, dispersion curves, vibrational properties

Speaker: Mr said TALBAOUI (Laboratory of Materials Physics)

92 A HAWC's Eye View on Supernova Remnants

For the HAWC Collaboration. Supernova Remnants (SNRs) have long been postulated to be the main sources of Galactic Cosmic Rays (CRs) up to the knee. However, while some SNRs have been shown to be CR accelerators, none of them have been confirmed to accelerate CRs beyond hundreds of TeV. The TeV gamma-ray emission from SNRs provides important information about the maximum energies to which CRs are being accelerated in SNRs. The High-Altidude Water Cherenkov Observatory (HAWC) is a wide field-of-view TeV gamma-ray survey observatory continuously observing the northern gamma-ray sky. In this presentation, we will give an overview of recent measurements of VHE gamma-ray emission from SNRs with HAWC. Special emphasis will be given to modeling the GeV-TeV gamma-ray emission from the gamma Cygni SNR, a middle-aged SNR in the Cygnus region.

Speaker: Dr Henrike Fleischhack Fleischhack (Michigan Tech)

93 A Likelihood Approach for Dark Matter Searches Around the Galactic Center with VERITAS

Revealing the nature of Dark Matter (DM) is a key objective of the current physical paradigm. Due to its predicted DM density at sub-pc distances, the Galactic Center should have a high number of DM interactions, making it a primary astrophysical source for DM studies. Various particle theories predict that DM annihilations over astrophysical scales can result in a gamma-ray flux. VERITAS is a terrestrial gamma-ray telescope in Arizona, USA, sensitive to gamma rays from 85 GeV to 30 TeV. It has accumulated ~108 hours of observations on the Galactic Center from 2010 to 2016. Major challenges when analyzing sky regions like the Galactic Center include modeling the diffuse emission from the galactic plane and the point source at the Galactic Center. By using a likelihood method, the software package ctools can fit multiple spatially- and energy-dependent models to address these complications. In this talk, I will present this new method for constraining DM mass and cross-sections from Galactic Center gamma-ray observations by VERITAS.

Speaker: Mr Nathan Kelley-Hoskins (DESY)

94 A Reconstruction Method for Extensive Air Shower Arrays Using Monte Carlo Based Templates with a Likelihood Approach

Traditionally for the extensive air shower arrays, the reconstruction of the gamma-ray induced air showers properties: such as core, energy and the depth of the shower maximum (X$_{max}$) is done by the model-dependent fit of the observed lateral amplitude distribution. This approach has certain disadvantages owing to the limitations of the fit models and procedures. To ameliorate this, we present the functionality of a Monte Carlo template based likelihood fit method, its usability, and advantages over a model dependent fit method. In contrast to the model dependent fit methods, the shower properties are reconstructed by fitting the observed lateral amplitude distribution of a gamma-ray induced air shower against an expected probability distribution using a likelihood approach. Additionally, the goodness of fit of the method gives us the gamma-hadron rejection power. Finally, one crucial advantage of this method is its easy adaptability for the mixed type particle detector arrays. As an example, we show its working for the High Altitude Water Cherenkov (HAWC) gamma-ray observatory and combined with its upcoming upgrade with a sparse outrigger array.

Speaker: Mr Vikas Joshi (Max-Planck-Institut für Kernphysik)

95 AGN outflows as neutrino sources: an observational test

Over the last few years the IceCube Neutrino Telescope has reported the first observations of an high-energy astrophysical neutrino flux. Recently, these observations have been strengthened by the publication of a sample of 82 high-energy starting events (HESE), and 36 high-energy muon neutrino tracks. Many different scenarios for the astrophysical origin of the IceCube neutrinos have been explored, but no clear answer has yet emerged. Among the possible sources, blazars are so far the most supported by the data, nevertheless their maximum contribution to the astrophysical neutrino flux has been constrained to be less than 27 per cent. We consider here a new, possible contributing class of neutrino emitters: AGN Outflows. We present here the results of quantitative tests, exploring the possible connection between IceCube neutrinos and AGN objects displaying outflows or outflow-like properties.

Speaker: Mr Andrea Turcati (Technical University Munich)

96 All-Sky Dark Matter Searches with HAWC

The High Altitude Water Cherenkov Observatory (HAWC) is a very high energy (500 GeV to 100 TeV) gamma ray detector located in southern Mexico. HAWC has both a wide field of a view and near-continuous duty cycle, making it ideal for unbiased sky surveys. We use HAWC data to perform such a search for gamma ray signals from "dark dwarfs"; dark matter sub-halos with no optical counterpart. There should be hundreds of these dark dwarfs in the HAWC field-of-view. We see no significant signals from these, so we use our results to set upper limits on dark matter annihilation across HAWC's view of the sky.

Speaker: Mr Joseph Lundeen (Los Alamos National Laboratory)

97 All-Sky Search for Transient Neutrino Sources with IceCube in Real-Time

The IceCube neutrino observatory is a 1 km³ detector deployed deep into the Antarctic ice sheet. While IceCube has recently discovered a diffuse astrophysical flux of high energy neutrinos, its source is yet to be identified. With a field of view covering the whole sky and continuous data-taking, IceCube is capable of detecting transient sources when one or more high-energy neutrinos arrive, and sending out an alert in realtime to other observatories. Immediate triggering of follow-up observations in the optical, X-ray and gamma-ray regime will increase the discovery potential of astrophysical sources and potentially help to constrain phenomenological models of high-energy neutrino and gamma-ray emission. In this talk a new online analysis of IceCube events is presented. Designed for a realtime identification of neutrinos clustered in space and time, it provides an additional alert channel for events potentially originating from transient or variable sources. Additionally, the performance will be demonstrated by applying the analysis to archival data.

Speaker: Mr Thomas Kintscher (DESY)

98 AMON coincidence analysis of sub-threshold events from HAWC and LIGO-Virgo

The detection of an electromagnetic signal by Fermi-GBM, temporally and spatially coincident with the first detection of a gravitational wave (GW) coming from a neutron star merger (NSM) by LIGO-Virgo, set a new milestone in multi-messenger astronomy. It enabled an unprecedented follow-up campaign of the event that allowed the identification and monitoring of the source. With improved sensitivities, several of these events are expected to be detected in the next observation run of LIGO-Virgo, starting early 2019. Given the NSM horizon for O3, very high energy transient counterparts may be observed. In this context, the HAWC observatory, sensitive to very high energy gamma rays between ~0.3-100TeV, is well suited to look for GW counterparts due to its large field of view and ~95% duty cycle. We will show preliminary results on TeV gamma ray and gravitational wave transient analysis in the context of the Astrophysical Multi-messenger Observatory Network (AMON). AMON has already shown its capabilities to perform coincidence analysis by the combination of sub-threshold neutrino, cosmic-ray, gamma-rays. The potential inclusion of gravitational waves is ongoing and subject of this contribution. We will present a novel likelihood ratio framework analysis, discuss the advantages of using astrophysical distribution of galaxies and the real time response of AMON in the next observation run O3.

Poster AMONTeVPA_Poster_v2.pdf

99 An improved photo-nuclear cross section model for simulations of UHECR sources and extragalactic propagation

The transport of Ultra-High Energy Cosmic Rays (UHECR) through photon target fields requires a model for photo-nuclear interactions. The photo-meson energy regime around 150 MeV in nucleus rest frame is relevant for the production of pions off UHECR nuclei and successively for astrophysical and cosmogenic neutrinos. The models in present theoretical calculations, including codes like CRPropa, use a simple approach, which relies on the assumption that the photon interacts with a single quasi-free nucleon, while the rest of the nucleus remains intact. This model neglects nuclear effects such as the fragmentation of the remnant, the pion re-absorption and the broadening of s-channel resonances in nuclear matter or the photon-emission from de-excitation. Further, it has to assume some scaling relation of the total non-elastic photo-nuclear cross section with the nuclear mass. We present extensions to this so-called superposition model to address the mass scaling of the nonelastic cross sections and fragmentation of the remnant nucleus. The impact of these extensions is evaluated through simulations of UHECR accelerators and astrophysical neutrino production sites using the NeuCosmA framework.

Speaker: Leonel Morejon (DESY)

100 Astroparticle constraints from lensing time delay measurements at different wavelengths

The use of gravitational time delays of macro-lenses to constrain the photon mass and the Lorentz Invariance Violation scale is investigated. The influence of photon masses on the measured time delays of macro-lenses is derived. The sensitivity of time delays to the photon mass is illustrated by a bound obtained from 3 AGN which have measurements in several passbands. The bound obtained is comparable to the limit with the deflection of radio waves by the Sun. A similar formalism is applied to obtain deviations of the macro-Lens time delay due to Lorentz invariance violating effects in the propagation of high energy photons. The bounds on the Lorentz invariance scale obtained are much weaker than those obtained by high energy and very high energy instruments, but are independent of source emission models.

Speaker: Jean-François Glicenstein (IRFU, CEA-Saclay)

101 Baryogenesis via leptogenesis in multi-field inflation

In multi-field reheating after modular $j$-inflation we investigate the conditions under which baryogenesis via non-thermal leptogenesis can be successfully realized. We introduce three heavy right-handed neutrinos to the non-supersymmetric standard model of particle physics, assuming hierarchical neutrino masses. Considering a typical mass for the first right-handed neutrino of the order of $10^{11}~GeV$, suggested from the seesaw mechanism and also from concrete $SO(10)$ grand unification models, we obtain the allowed parameter space for viable baryogenesis. An upper bound for the inflaton mass as well as a lower bound for its branching ratio to the pair of lightest right-handed neutrinos are found and reported.

Speaker: Dr Nelson Videla (Pontifical Catholic University of Valparaíso)

102 Black Holes' Dark Dress: The impact of local Dark Matter halos on the mergers of primordial black hole binaries

The observation of gravitational waves from binary black hole mergers has renewed interest in the possibility of primordial black holes (PBHs) that are around 10 to 100 times more massive than the Sun. Such PBHs may form large numbers of binaries before matter-radiation equality and, if these binaries survive until today, they may contribute to the merger rate observable by LIGO and Virgo. However, if PBHs are a sub-dominant fraction of the Dark Matter (DM), they will be dressed in local DM halos which may disrupt the binaries through dynamical friction. I will present the results of N-body simulations and analytic estimates, studying the impact of this 'dark dress'. While the size and shape of PBH binaries is dramatically altered by local DM halos, there is a surprisingly subtle effect on the rate of mergers expected today. Limits on the merger rate observed by LIGO-Virgo may be translated into bounds on the fraction of DM in the form of PBHs. I will argue that our calculations place such bounds on a more solid footing, constraining the fraction of DM in the form of 10-300 solar mass PBHs to be around $10^{-3}$ or less. The techniques I present also pave the way for future studies of DM halos around astrophysical black holes and their impact on gravitational wave signals.

Speaker: Dr Bradley Kavanagh (GRAPPA, University of Amsterdam)

103 Boosting the Annihilation Rate with Ultracompact Minihalos

Cosmological inflation generates primordial density perturbations which are scale-free on observable scales but that may be considerably larger on smaller scales. The boosted power spectrum at small scales leads to increased formation of dense, small-scale structure at early times, enhancing the present-day annihilation rate of annihilating dark matter. In this work, we show how to compute the impact of a power spectrum predicted by an inflationary model on WIMP indirect detection, leading to constraints on the WIMP-inflation parameter space within the context of axion inflation and establishing a procedure for similar future inquiries.

Speaker: Mr Joshua Foster (University of Michigan)

104 Bounds on Inelastic Dark Matter from Neutrino Detectors

Models of TeV-scale dark matter are severely constrained by increasingly precise direct detection experiments. One paradigm which can evade these bounds is Inelastic Dark Matter (iDM), where a nontrivial dark sector contains two particles with a small mass splitting $\delta$. A typical example is a supersymmetric model in which the two lightest Higgsinos have TeV-scale masses, and the heavier one decays to the (stable) lighter one by emitting a photon of energy $\delta = \mathcal{O}(100 keV)$. Previous works have bounded the iDM parameter space using the kinematics of iDM scattering in direct detection experiments. In our scenario, we observe that dark matter can upscatter against heavy elements inside the earth, travel to and decay inside of existing experiments, such as the Borexino detector at Gran Sasso. Due to unique modulation signals, it is possible to improve on previous constraints on iDM scenarios using existing data from Borexino.

Speaker: Dr Joshua Eby (Weizmann Institute of Science)

105 Cherenkov Telescope Array event reconstruction with ImPACT

In this presentation, the performance of a template-based event reconstruction algorithm will be shown for the first time for the Cherenkov Telescope Array (CTA), the next gen- eration ground-based instrument for gamma-ray astronomy. In the Image Pixel-wise fit for Atmospheric Cherenkov Telescopes (ImPACT) the charge measured in each camera pixel of each telescope during an extended air shower (EAS) event is compared to an expected image template through a maximum likelihood fit. This allows us to reconstruct the direction and energy of the primary EAS particle and to accurately discriminate between gamma-ray sig- nals and cosmic-ray background. This method already led to an improved H.E.S.S. sensitivity and angular resolution that was used successfully to study the extension of RX J1713.7-3946 and the Crab nebula. For CTA, the study is based on air shower Monte-Carlo simulations and a detailed ray- tracing of the produced Cherenkov light within the individual telescopes of the CTA layout of the Southern Hemisphere. We will show that with ImPACT high angular resolutions and sensitivities can be reached over the full energy range of CTA between 20 GeV and 300 TeV. With the same data quality selection cuts applied, for most energies a significant enhancement in both properties is achievable compared to the standard analysis. This will reduce observation time needed for detection of TeV gamma-sources and improve the accuracy of morphological studies of complex sources.

Speaker: Mrs Sabina Pürckhauer (Max-Planck Institut für Kernphysik)

106 Colored scotogenic

We propose a simple theory for the idea that cosmological dark matter (DM) may be present today mainly in the form of stable neutral hadronic thermal relics. In our model neutrino masses arise radiatively from the exchange of colored DM constituents, giving a common origin for both dark matter and neutrino mass. The exact conservation of B−L symmetry ensures dark matter stability and the Dirac nature of neutrinos. The theory can be falsified by dark matter nuclear recoil direct detection experiments, leading also to possible signals at a next generation hadron collider.

Speaker: Prof. Diego Restrepo (Professor)

107 Constraints on MeV dark matter using neutrino detectors and their implication for the 21-cm results

The recent results of the EDGES collaboration indicate that during the era of reionization, the primordial gas was much colder than expected. The cooling of the gas could be explained by interactions between dark matter (DM) and particles in the primordial gas. Constraints from cosmology and particle experiments indicate that this DM should be light (~10-80 MeV), mili-charged, and only make up a small fraction of the total amount of DM. Several constraints on the DM parameter space have already been made. We explore the still unconstrained space in the case that the mili-charged DM makes up for ~1% of the total DM, through the scenario in which this DM annihilates only into muon- and tau neutrinos. We set upper limits on the annihilation cross section using Super-Kamiokande data, and predict the upper limit that could be reached by future experiments like Hyper-Kamiokande. We show that these experiments might be able to reach the relevant parameter space predicted by EDGES, and therefore be capable to probe this DM scenario.

Speaker: Ms Niki Klop (GRAPPA institute, University of Amsterdam)

108 Construction of a Schwarzschild-Couder telescope as a candidate for the Cherenkov Telescope Array: status and performance of the optical alignment system

The 9.7m Schwarzschild-Couder (SC) medium-sized telescope is a candidate for the Cherenkov Telescope Array (CTA). It exploits a novel aplanatic two-mirror optical design to provide a large field of view of 8 degrees and improved angular resolution across the whole field of view compared to single-mirror designs. In addition, the reduced plate scale of the camera allows the use of compact, high quantum efficiency photon detectors, such as silicon photomultipliers, providing an unprecedented spatial sampling of showers. The realization of such an optical design implies the challenging production of large aspherical mirrors and the implementation of a sophisticated custom alignment system capable of achieving submillimeter precision. The construction of a prototype Schwarzschild-Couder telescope (pSCT) started in June 2015 at the Fred Lawrence Whipple Observatory in Southern Arizona and is nearing completion. In this contribution, we report on the design, implementation, and performance of the pSCT optical alignment system.

Speaker: Mr Andrii Petrashyk (Columbia University)

Poster TeVPA2018_pSCT_OpticsImplementation-AP_v2.pdf

109 CTA Potential in PeVatron Search

One of the major scientific objectives of the future Cherenkov Telescope Array (CTA) Observatory is the search of PeVatrons. PeVatrons are the cosmic-ray factories able to accelerate nuclei at least up to Peta-electronvolt (1 PeV = 10$^{15}$ eV) energies. CTA will perform the first survey of the full Galactic plane at TeV energies and beyond with unprecedented sensitivity. The determination of efficient criteria to identify PeVatron candidates during the survey observations is essential in order to trigger deeper observations. Here, we propose a study based on a full simulation to determine these criteria. The outcome of the study will be a PeVatron figure of merit, which is a metric that provides relations between spectral parameters, observation times and spectral cut-off energy lower limit. In order to test the criteria, results of simulations on known PeVatron candidate sources and their parent particle spectra will be presented and discussed.

Speaker: Dr Ekrem Oguzhan Angüner (CPPM)

110 Dark Matter Accretion in Neutron Stars

If DM interacts with nucleons and/or electrons it can be trapped by astrophysical objects such as the Sun or neutron stars. Elastic scattering of a DM particle with ordinary matter can in particular reduce the kinetic energy of the DM particle when it passes through these stars, such that its speed passes below the corresponding escape velocity. Once gravitationally trapped, DM undergoes further scatterings until it gets gravitationally confined inside the star and move towards the center. This possibility is interesting in many ways. For the Sun it is mostly interesting because it can leads to DM indirect detection signals in the form of a neutrino flux from DM annihilation. For a neutron star, DM accumulating in the center could form a dense core which could gravitationally collapse into a black hole. In this talk I will present how we have reconsidered in details neutron star DM accretion, incorporating an all series of effects which had not been considered (or only partially incorporated) before. Among those, we have performed a proper calculation of the DM accretion rate, taking into account the highly degenerate nature of the neutron plasma in the neutron star.  Combined with realistic neutron star profiles, for DM masses below 1 GeV, our results are several order of magnitudes smaller than previously reported in the literature. Secondly, a new treatment of DM thermalization has let us investigate the time evolution of the DM cloud. Using these improvements, I will present our updated constraints on DM, from neutron stars collapsing into black holes.

Speaker: Mr Yoann GÉNOLINI (Univ. of Brussels (ULB))

111 Dark matter relic density for a light vector mediator

In collider experiments, such as the Large Hadron Collider, an unknown particle could be produced from a pair of quarks in proton-proton collisions. In simplified dark matter models, this particle could then decay either into WIMP (Weakly-Interacting Massive Particles) dark matter or into Standard Model particles, acting as a mediator between ordinary matter and dark matter. From such a simplified model, we consider a light mediator Z' (m_Z' < 300 GeV) and test different scenarios of the couplings to dark matter and Standard Model matter of this mediator to see the impact these changes have on the relic density of dark matter, using MadDM and micrOMEGAs for the calculations. The today observable abundance of dark matter can be achieved through different mechanisms, such as freeze-out and freeze-in. In the freeze-out scenario, the initial dark matter abundance is high and decreases due to annihilation and decay processes as the universe cools down. Conversely, in the freeze-in case, there is only a small amount of dark matter initially, and more dark matter is produced as the universe evolves. Additionally to investigating the relic density from the freeze-out production of dark matter, we use the freeze-in module in micrOMEGAs to calculate the relic density for even smaller couplings to dark matter and Standard Model matter.

Poster RelicDensityVectorMediator.pdf

112 Diffusive shock acceleration in the young supernova remnant G1.9+0.3

The very young Supernova remnant G1.9+0.3 is an interesting target for next generation gamma-ray observatories. So far the remnant is only detected in the radio and the X-ray bands but its young age and inferred shock speed of 14,000km/s should make it an efficient particle accelerator. We carry out spherical symmetric 1-D simulations where we simultaneously solve the transport equations for the cosmic rays, the hydrodynamical flow and the magnetic turbulence. With our test-particle simulations we are able to reproduce the observed radio and x-ray spectra together with the radio and x-ray profiles in the east-west direction and the observed radio-flux increase of about 1.2%/yr.

Poster Poster.pdf

113 Directional Search for Dark Matter Using Nuclear Emulsion

A variety of experiments have been developed over the past decades, aiming at the detection of Weakly Interactive Massive Particles (WIMPs) via their scattering in an instrumented medium. The sensitivity of these experiments has improved with a tremendous speed, thanks to a constant development of detectors and analysis methods. Detectors capable of reconstructing the direction of the nuclear recoil induced by the WIMP scattering are opening a new frontier to possibly extend Dark Matter searches beyond the neutrino background. Exploiting directionality would also give a proof of the galactic origin of dark matter making it possible to have a clear and unambiguous signal to background separation. The NEWSdm experiment, based on nuclear emulsions, is a new experiment proposal intended to measure the direction of WIMP-induced nuclear recoils with a solid-state detector, thus with a high sensitivity. We discuss the discovery potential of a directional experiment based on the use of a solid target made of newly developed nuclear emulsions and novel read-out systems achieving nanometric resolution. We also report results of a technical test conducted in Gran Sasso.

Speaker: Prof. A. MURAT GULER (Middle East Technical University)

114 Energy dependent time lag search in blazar emissions with H.E.S.S.

In the past 15 years, Cherenkov Telescopes have detected various minute-scale flares of AGNs in the energy range above 100 GeV. This important sample allows for measurements of corresponding light curves and energy spectra leading to a precise determination of possible photon energy dependent time delays. Analyses were performed in order to study possible effects of these distant and variable sources on the emission of photons. Notably, the search for energy-dependent time-lags allows for constraining astrophysical models and also greatly contributes to fundamental physics such as searches for a possible violation of the Lorentz Invariance. In the proposed presentation, both physical topics will be addressed while focusing on the time-lag measurements in AGN flares detected by the H.E.S.S. experiment. Methods to measure time lag will be presented, as well as the preliminary analysis of a flare observed by H.E.S.S.

Speaker: Mr Cédric Perennes (LPNHE - Paris)

115 Estimating Spectra with the Dortmund Spectrum Estimation Algorithm

Obtaining the energy spectrum of an astrophysical source is crucial for our understanding of the source properties and the underlying physical principles, e.g. the acceleration of cosmic rays. In Imaging Air Cherenkov Astronomy and neutrino astronomy, however, the reconstruction of spectra is hindered by the fact, that the energy of the primary particle cannot be accessed experimentally, but has to be inferred from secondary particles. Mathematically this task corresponds to an inverse problem, generally described by the Fredholm integral equation of the first kind. Solving the Fredholm integral equation is generally referred to as unfolding or deconvolution. In our talk, we present the Dortmund Spectrum Estimation Algorithm (DSEA), which is capable of solving inverse problems by utilizing state-of-the-art machine learning techniques. DSEA translates the unfolding in a multinominal classification task, which is then solved by an -- at least in principle -- arbitrary classification algorithm. The reconstruction quality of DSEA is comparable to the performance achieved using other state-of-the-art unfolding algorithms, but in contrast those, DSEA fully retains the information on the individual examples. This unique property allows researchers to study spectra as a function of other variable, e.g. time or zenith angle. Although the reconstruction of spectra is equally important in Imaging Cherenkov- and neutrino astronomy, we will focus on results obtained using simulated events from the Cherenkov telescopes FACT and MAGIC. DSEA is part of an open source software package development in project C3 of the Collborative Research Center 876.

Speaker: Mr Mirko Bunse (TU Dortmund)

116 Exploring the privileged status of TXS 0506+056 as an emitter of astrophysical neutrinos

Among the various categories of AGN, blazars, and especially BL-Lacs, are the prime candidate sources of TeV astrophysical neutrinos, due to their high luminosity at very high-energy (VHE) range, and high and frequent activity periods. In their flaring state, non-thermal emission is expected through the Synchrotron Self-Compton (SSC) of the electron populations, however a contribution related to protons is also expected through the photopion interaction, releasing neutrino and gamma rays in the process. We present the annually and semi-annually binned differential fluxes of 3 blazars: TXS 0506+056, OP 313 and Mkn 421, over the entire observation period of the Fermi experiment (3FGL catalog). We extrapolate the emission to higher energies (looking at the spectral features), obtain the expected corresponding neutrino fluxes (under the hypothesis of fully hadronic emission) and compare them with the point-source sensitivity of IceCube neutrino telescope. While Mkn 421 is a well monitored and relatively close BL-Lac, OP 313 and TXS 0506+056 were selected due to their similar characteristics and spatial coincidence with the direction of two extraterrestrial neutrino track events in IceCube. The latter-most has also been reported by Fermi and MAGIC to have been observed in a flaring state during the time of the spatially coincident neutrino event of IceCube. We calculate the duty cycles and the total power emitted during the flaring states for these sources, and show that although being sensitive to all three sources during their active states, IceCube does not observe the expected neutrino signal from OP 313 and Mkn 421 during their flares while TXS 0506+056 seems to show a positive multi-wavelength correlation. Possible reasons for this unique correlation are also discussed.

Speaker: Ankur Sharma (INFN Pisa)

117 Extragalactic photon--axion-like particle oscillations

Axion-like particles (ALPs) are very light, neutral, pseudo-scalar bosons which are supposed to interact with two photons. They can give rise to very interesting astrophysical effects taking place in the very-high energy band and above (10 GeV – 1000 TeV) when an external magnetic field is present. We analyze the propagation of the photon-ALP beam generated as pure photons at the jet base of a BL Lac, we study the photon-ALP oscillations during its path up to us while crossing the BL Lac magnetic field, the intergalactic magnetic field which we describe by means of an improved model and the Milky Way magnetic field. Our results are of great importance for the new generation of gamma-ray observatories like CTA, HAWC, GAMMA-400, LHAASO and TAIGA-HiSCORE.

Speaker: Dr Giorgio Galanti (INAF, Osservatorio Astronomico di Brera)

118 Fermi particle acceleration in trans-relativistic shocks with magnetic field amplification

First-order Fermi particle acceleration in supernova remnant (SNR) shocks is generally considered as the most likely production mechanism for the bulk of the cosmic rays (CRs), i.e., those with energies below the knee at $\sim 10^{15}$ eV. The SNR origin of higher energy CRs remains uncertain since the shock speeds of typical SNRs are too small to produce CRs above $\sim 10^{16}$ eV in the time and space limits of the expanding blast wave. Recently, however, a class of relativistic supernovae has been discovered having trans-relativistic ejecta speeds. Fermi acceleration in trans-relativistic shocks differs importantly from that in either non-relativistic or ultra-relativistic shocks and may allow CR production to energies well above the knee. A fundamental aspect of efficient Fermi acceleration in all shocks is the production of magnetic turbulence in the shock precursor by back streaming CRs. We have recently included a largely self-consistent calculation of magnetic field amplification (MFA) in a nonlinear Monte Carlo simulation of trans-relativistic shocks including the resonant streaming instability and two non-resonant instabilities: the short-wavelength Bell instability and the long-wavelength current-driven instability. We will describe initial results from this work.

Speaker: Prof. Don Ellison (North Carolina State University)

119 First Engineering Results from the First Micro-X Sounding Rocket Flight

The Micro-X High Resolution Microcalorimeter X-Ray Imaging Rocket is a sounding rocket mission that launched on July 22, 2018. This was the first successful operation of Transition Edge Sensors (TESs) and SQUID Time-Division Multiplexing in space. This milestone demonstrates the flight readiness of these technologies and establishes a new type of detector for X-ray astronomy. Micro-X is designed to observe Supernova Remnants and BSM X-ray interactions, like those proposed from keV-scale sterile neutrino dark matter. This instrument combines the excellent energy resolution of TES microcalorimeters with the imaging capabilities of a conical imaging mirror to map extended and point X-ray sources with a unique combination of energy and spatial resolution. We present the engineering results of the first flight, with special emphasis on the successful performance of the cryostat and electronics within the challenging conditions of a sounding rocket flight. While a rocket pointing error led to minimal time on-target, the science instrument operated as expected, and data from this flight will be used to establish background flux limits and as calibration data in preparation for future flights. Co-Authors: Micro-X collaboration

Speaker: Antonia Hubbard (Northwestern University)

120 First light of the HAWC high energy upgrade

The High Altitude Water Cherenkov (HAWC) γ-ray observatory is fully operational since march 2015 in central Mexico. It is a Water Cherenkov Detector (WCD) consisting of 300 tanks filled with purified water, each instrumented with 4 photomultiplier tubes. They record, via the cherenkov light produced in the water, the secondary particles from atmospheric air showers of energy ranging from 0.1 to 100 TeV. Its sensitivity to TeV γ-ray sources is one order of magnitude better than the previous generation of WCD. HAWC is currently undergoing a major upgrade with the addition of a sparse array of 345 smaller tanks around the main array, extending the current instrumented area from 22500 m2 to 100000 m2. The main objective is to enable accurate reconstruction of multi-TeV showers whose core and footprint is not well contained inside the main array. We will present the status of the HAWC upgrade as well as the first data and the improvement in sensitivity achieved with the upgraded version.

Speaker: Ms Armelle Jardin-Blicq (Max Planck Instiute für Kernphysik)

121 Flavor And Energy Inference For The High-Energy IceCube Neutrinos And Applications In Quantum Spacetime Models

I will present a flavor and energy inference analysis (Astroparticle Physics, Volume 101, 2018) for each high-energy neutrino event observed by the IceCube observatory during six years of data taking. For each event the main observables in the IceCube detector are the deposited energy and the event topology (showers or tracks) produced by the Cherenkov light by the transit through a medium of charged particles created in neutrino interactions. Using Bayesian inference and Markov chain Monte Carlo methods I will show how to reconstruct from these observables the properties of the astrophysical neutrino which generated such event. In the end, I will expose briefly, in the contest of a multi-messenger astrophysics, an interesting speculation regarding some aspects of IceCube data which may be manifestations of quantum-gravity-modified laws of propagation for neutrinos. A speculation which, as testified by some recent publications (Nat. Astron. 1, 0139, 2017), has attracted an increasing interest.

Speaker: Mr Giacomo D'Amico (University of Rome "La Sapienza")

122 Galactic Gamma-Ray Astronomy with the Southern Gamma-Ray Survey Observatory

On behalf of the SGSO Consortium. The field of Very-High-Energy (VHE, E>100 GeV) gamma-ray astronomy is entering an era of precision measurements. Over the last decade, innovations in instrumentation have led to a drastically improved understanding of the most energetic objects in the Universe. New results by the High Altitude Water Cherenkov Observatory (HAWC) have shown the unique insights that large-field-of-view survey instruments like HAWC can provide to the field. The recent 2HWC catalog and other publications have revealed gamma-ray emission from several large extended sources such as TeV halos sourrounding pulsar-wind nebulae. Synergies between ground- and space-based survey and pointing instruments have already led to the identification of several new sources and source candidates. In this presentation, we will explore the potential of the Southern Gamma-Ray Survey Observatory (SGSO) for Galactic gamma-ray astronomy. SGSO is a proposed next-generation, ground-based, wide-field-of-view TeV gamma-ray observatory. It will be sensitive to gamma rays in the energy range from 100 GeV to hundreds of TeV. In particular, we will discuss further study of TeV halos, the search for large extended structures such as possible counterparts of the Fermi bubbles at TeV energies, gamma-ray emission from Molecular clouds, and the search for galactic transients.

Speaker: Dr Henrike Fleischhack Fleischhack (Michigan Tech)

123 Gamma-rays from radio galaxies produced in the external blob radiation model

Gamma-ray emitting FR I type radio galaxies are expected to be aligned at large angles to the line of sight. We consider a scenario which naturally explains the energetic gamma-ray emission from radio galaxies. It is proposed that two emission regions are present in the jet at this same moment, the inner fast moving blob produces radiation strongly collimated along the jet axis and the outer blob which isotropic electrons up-scatter mono-directional soft radiation from the inner blob preferentially in the direction opposite to the jet motion. Gamma-rays from the outer blob are emitted at a relatively large angles to the jet axis in the observer's reference frame. We provide the example modeling of the emission from the FR I type radio galaxy NGC 1275.

Speaker: Prof. Wlodek Bednarek (University of Lodz)

124 Gas active targets: a window to high-energy gamma-ray polarimetry with conversions to e+e-; experimental demonstration with the HARPO TPC (time projection chamber) prototype.

gamma-ray astronomy is polarization-blind as no significant polarimetry of a cosmic source has been performed since the [OSO-8 measurement on the Crab nebula][1] in the X-ray band. gamma-ray polarimetry would enable to [tag the curvature-synchrotron radiation transition in pulsars][2], to [decipher leptonic from hadronic radiation models for blazars][3] .. and [much more][4]. We [demonstrated][5] that with a low-density homogeneous active target such as a gas TPC (time projection chamber), the single-track angular resolution is so good after a low radiation-length thickness that polarimetry should be possible with gamma conversions to e+e- pairs. **With a TPC prototype in a gamma-ray beam, we demonstrated experimentally the effective polarimetry with an excellent polarization-asymmetry dilution** [AstroPart. Phys. 97 (2018) 10][6]. Spin-offs of interest to the community: An analytical analysis of the single-track angular resolution with an optimal tracking à la Kalman, an optimal method to measure a track momentum in a non-magnetic tracker from the analysis of the deflections due to multiple scattering ([Kalman][7] helping [Molière][8]), interest to silicon-detector based telescopes (Fermi-LAT, AGILE, e-ASTROGAM, AMEGO) [NIM A 867 (2017) 182][9]. An exact Monte carlo event generator of the five-dimensional (5D) Bethe-Heitler differential cross section (polarized or not, nuclear or triplet conversion, pure QED or with electron cloud screening) and strictly energy-momentum conserving, [to appear in NIM A][10]. Good hope of a deployment of the G4BetheHeitler5DModel physics model in the 10.5beta Geant4 release at the end of June 2018. [1]: http://dx.doi.org/10.1086/182648 [2]: http://inspirehep.net/record/1641719 [3]: http://inspirehep.net/record/1242827 [4]: https://inspirehep.net/record/1498288 [5]: http://inspirehep.net/record/1242601 [6]: https://inspirehep.net/record/1606056 [7]: http://inspirehep.net/record/259509 [8]: http://zfn.mpdl.mpg.de/data/Reihe_A/10/ZNA-1955-10a-0177.pdf [9]: https://inspirehep.net/record/1605726 [10]: https://doi.org/10.1016/j.nima.2018.05.021

Speaker: Dr Denis Bernard (LLR, CNRS/IN2P3)

Poster poster.pdf

125 GRAND: The Giant Radio Array for Neutrino Detection

Progress in finding the origin of ultra-high-energy cosmic rays (UHECRs) will come from discovering the secondary UHE neutrinos produced in UHECR interactions. Yet, the flux of UHE neutrinos may lie beyond the reach of existing detectors and their possible upgrades. GRAND is a planned large-scale UHE observatory designed to discover UHE neutrinos even if their flux is low. It will do so by measuring the radio emission from extensive air showers triggered by UHE particles in the atmosphere --- not only neutrinos, but also cosmic rays and gamma rays. For UHE neutrinos, GRAND aims to reach a sensitivity of $\sim$$10^{-10}$ GeV cm$^{-2}$ s$^{-1}$ sr$^{-1}$ in 3 years, a factor-of-100 improvement over potential upgrades of existing detectors. Further, GRAND aims for an aperture to cosmic rays above $10^{10}$ GeV that is 20 times larger than in Auger, and a sensitivity to a flux of UHE gamma rays that is 10 times better. Besides, GRAND will be a powerful instrument for radioastronomy. In this talk, I will showcase the rich science program of GRAND, its design, and its construction status and plans.

Speaker: Dr Mauricio Bustamante (Niels Bohr Institute)

126 GRB Observations with H.E.S.S II

Fermi-LAT observations have proven that GeV gamma-ray emission is a relatively common feature for many gamma-ray bursts (GRBs). However, the relatively low effective area of space detectors implies low statistics for the highest energy photons which impedes detailed physical interpretation. The highest energy photon detected by LAT reached 95 GeV, a range which is well within reach for ground-based Imaging Atmospheric Cherenkov Telescopes (IACTs). As their effective area is orders of magnitude larger than that of Fermi-LAT, the IACT detection of high-energy gamma-rays from a GRB promises a wealth of detailed information. The High Energy Stereoscopic System (H.E.S.S.) is an IACT array belonging to the current generation of such instruments. It is the first hybrid IACT array composed of four 12 m diameter and one 28 m diameter telescopes. The large light collection area of 600 $m^2$ of the large telescope is perfectly suitable to observe gamma-rays between 50 GeV and 100 GeV with unprecedented sensitivity. Combined with the capability to rapidly and fully automatically react to alerts, H.E.S.S. is one of the most promising instruments to probe or constrain short time scale emission of GRBs at very high energies. In this contribution we will describe the H.E.S.S. GRB observation program, trigger conditions of GRB observations and analyses of several tens of GRBs. This compilation of observations represents the largest list of GRB observations with IACTs and provides numerous inputs for GRB modeling at very high energy.

Speaker: Ms Ruiz-Velasco Edna (Max-Planck-Institut für Kernphysik)

Poster PosterGRB_TeVPA_(3).pdf

127 H.E.S.S. observations of the flaring gravitationally lensed galaxy PKS 1830-211

PKS 1830-211 is a known macrolensed AGN located at a redshift of z=2.5. Its high energy gamma ray emission has been detected with the Fermi-LAT instrument and evidence for lensing was obtained by several authors from its high energy data.?Aims. Observations of PKS 1830-211 were taken with the H.E.S.S. array of Imaging Atmospheric Cherenkov Telescopes in August 2014, following a flare alert by the Fermi- LAT collaboration. The H.E.S.S observations were aimed at detecting a gamma ray flare delayed by 20-27 days from the alert flare, as expected from observations at other wavelengths. An upper limit on PKS 1830-211 flux above 100 GeV is computed and compared to the extrapolation of the Fermi-LAT flare spectrum. Potential constraint on EBL for future observations of this source are studied.

Speaker: Jean-François Glicenstein (IRFU, CEA-Saclay)

128 H.E.S.S. observations of the FSRQ PKS 1510-089 and its long-term evolution

The governing process behind the variability of blazars is still unknown. Hence, the collection of long-term data on individual sources is an important step in order to unlock this unknown. The flat spectrum radio quasar (FSRQ) PKS 1510-089 has been observed by H.E.S.S. at VHE gamma-rays (E>100GeV) since the discorvery in 2009. A much denser monitoring effort has been started in 2015 in order to achieve the importantd detection of PKS 1510-089 during quiescence. The latter implies efficient particle acceleration beyond pc-scales from the black hole, since at smaller distances the strong absorption by the BLR inhibits the emission of VHE photons. The monitoring is complement by data at HE gamma-rays (E>100MeV) from Fermi, as well as X-ray and optical data from Swift and ATOM. The densely sampled lightcurves allow for detailed correlation analyses -- yet, no obvious correlations can be found between the VHE lightcurve and the multiwavelength data sets, indicating a non-trivial interplay of the jet processes. This makes this FSRQ difficult to interpret within a unique theoretical framework.

Speaker: Dr Michael Zacharias (TPIV, Ruhr-Univseristät, Bochum, Germany)

129 H.E.S.S. searches for TeV gamma-rays associated to high-energy neutrinos with H.E.S.S.: the case of IceCube-170922A / TXS 0506-056

Fabian Schüssler on behalf of the H.E.S.S. Collaboration The detection of an astrophysical flux of high-energy neutrinos by IceCube is a major step forward in the search for the origin of cosmic rays, as this emission is expected to originate in hadronic interactions taking place in or near cosmic-ray accelerators. No neutrino point sources, or significant correlation with known astrophysical objects, have been identified in the IceCube data so far. The hadronic interactions responsible for the neutrino emission should also lead to the production of high-energy gamma rays. The search for neutrino sources can then be performed by studying the spatial and temporal correlations between neutrino events and very high energy (VHE, E > 100 GeV) gamma rays. We report here on the search for VHE gamma-ray emission at the reconstructed position of muon neutrino events detected by IceCube with the H.E.S.S. imaging air Cherenkov telescopes (IACTs). We will summarize searches for steady gamma-ray counterparts as well as the extensive program to perform prompt IACT observations of realtime IceCube neutrino event positions. A recent highlight of this program are the H.E.S.S. observations during the broad multi-wavelength campaign that followed the detection of the neutrino event IceCube-170922A arriving from a direction consistent with the location of a flaring gamma-ray blazar TXS 0506+056 in September 2017. We'll present the H.E.S.S. observations obtained within ~4h hours of the neutrino detection as well as a complementary search for gamma-ray emission at longer timescales and put them into the multi-wavelength and multi-messenger context.

Speaker: Dr Fabian Schussler (CEA-Saclay)

Poster HESS-Neutrinos_TeVPA2018_Schussler_Poster.pdf

130 Hadronic processes in structured jets of Cygnus X-1

Cygnus X-1 is the first Galactic source confirmed to host a black hole and has been observed since then across the whole electromagnetic spectrum. Recently, it was also detected in the 0.1-10 GeV band by Fermi/LAT and possibly detected at low significance by MAGIC during a flare. The source's non-thermal radiation is thought to originate from the relativistic jets launched by the black hole because of the flat radio spectrum and of the orbital-period dependence found in the high energy light curve. The processes that lead to this non-thermal emission are still debated, with both leptonic and hadronic deemed to be viable. The latter scenario requires protons to be accelerated up to hundreds of TeV by some natural mechanism. These particles can collide with other protons ejected by the companion star in the form of stellar wind or with the photons produced by the companion. These interactions lead to particle cascades and produce secondary electrons, $\gamma$-rays and neutrinos. In this work, we use for the first time a multi-zone, jet model parameterizing the magnetohydrodynamical profile, together with a self-consistent secondary cascade and radiation calculation, and apply it to the best yet simultaneous dataset of Cygnus X-1 in the hard state. We discuss which scenario, hadronic or leptonic, best describes the dataset, as well as some of the uncertainties in understanding the role of secondary electrons in the spectrum.

Speaker: Mr Dimitrios Kantzas (UvA/API/GRAPPA)

131 Hadronic radiation from the rotation powered white dwarf within the binary system AR Scorpii

AR Scorpii, close binary system of a rotation powered white dwarf and a low mass M type companion star, shows non-thermal emission extending up to the X-ray energy range. We propose that relativistic electrons and hadrons can be accelerated in a strongly magnetised, turbulent region formed in collision of a rotating white dwarf magnetosphere and a dense atmosphere of the M dwarf star. The non-thermal X-ray emission is produced either by the primary electrons or the secondary electron-positron pairs from decay of charged pions created in collisions of hadrons with the companion star atmosphere. We show that the accompanying gamma-ray emission (from decay of neutral pions) is expected to be on the detectability level of the present and/or the future satellite and Cherenkov telescopes.

Speaker: Prof. Wlodek Bednarek (The University of Lodz)

132 High-energy analysis optimisation for imaging atmospheric Cherenkov telescopes beyond 10 TeV

The High Energy Stereoscopic System (H.E.S.S.) is an array of Cherenkov telescopes in Namibia and operates in the energy range from a few tens of GeV to more than 50 TeV. Most of the very-high-energy sources visible with H.E.S.S. emit gamma rays with energies up to tens of TeV. Nominal analysis methods, however, are optimised for the TeV energy range and achieve the best sensitivity at $\sim$1 TeV. For higher energies, existing systems are mainly limited by gamma-ray statistics. The aim of the work presented here is to improve the sensitivity above 10 TeV by optimising analysis techniques and selection tools for the highest energies. Typically, events only within $\sim$2.5 deg offset are accepted in the standard H.E.S.S. analysis (physical field of view of the cameras). Extending this range up to $\sim$4.5 deg offset would lead to an increase of the effective field of view and photon statistics, and as a result, to an improvement of the sensitivity in the high-energy domain. An improved method that is capable of reconstructing events with offsets up to $\sim$4.5 deg will be presented in this contribution.

Speaker: Mrs Iryna Lypova (DESY, Zeuthen)

133 Improving the directional reconstruction of PeV hadronic cascades in IceCube

Many neutrino interactions measured by the IceCube Neutrino Observatory produce only hadronic showers, which appear as almost point-like light emission due to the large detector spacing (~125m). At PeV energies these showers often saturate the PMTs closest to the interaction vertex - thus the reconstruction has to rely on more diffused photons which requires precise understanding of the optical properties of the Antarctic ice. Muons produced in the hadronic showers carry information about the neutrino direction, and their Cherenkov light arrives earlier than the photons emitted by the electromagnetic component. A new reconstruction method has been developed which explicitly takes into account the muonic component of hadronic showers and is shown to be robust against systematic ice uncertainties. By applying the new reconstruction, the angular resolution of multi-PeV cascade events can be significantly improved. This will potentially enable follow-up studies of the highest-energy cascade events measured by IceCube.

Speaker: Mr Christian Haack (RWTH Aachen University)

134 Intrinsic spectral timelags in blazar TeV flares

Studying the arrival times of γ-ray photons according to their energy puts constraints fundamental physics such as Lorentz Invariance Violation (LIV) signatures but can also provide specific information about the emitting sources themselves. Observing the time evolution of AGN spectra can significantly constrain *in situ* physical parameters and radiative processes at work. A synchrotron-self Compton (SSC) time dependent model of blazar flares, built to analyse intrinsic time delays at γ-ray energies above 1 MeV, is used to produce light curves in different energy bands and to perform a dedicated study on each model parameter to evaluate their influence on the delay. The energy dependence of time delays which is obtained for standard cases can be of importance. Indeed, lags could potentially be detected by current instruments as well as by CTA in the coming years and could contribute to a better understanding of the source properties and radiative transfers. Moreover, the present upper limits found on LIV signatures can in fact be re-interpreted in terms of constraints put on blazars and flare scenarios.

Speaker: Mr Cédric Perennes (LPNHE - Paris)

135 Inverse Compton scattering and short Gamma-ray bursts

Very-high-energy (VHE) photon detections from Gamma-ray bursts (GRBs) can provide compelling evidences about the radiative processes, physical composition of the ejecta and acceleration processes. The synchrotron radiation can only explain photons with energies less than < 10 GeV. In the framework of GRB fireball, we present a theoretical model based on synchrotron self-Compton forward shocks to interpret the Fermi-LAT-detected bursts with photons larger than 10 GeV. We explore the range of microphysical parameters and circumburst densities that allow to interpret VHE photons. Collaborators: Dr. Simone Dicciara and Dra. Magadalena Gonzalez

Speaker: Dr Nissim Fraija (Astronomy Institute)

136 Inverse compton scattering model of the Crab Nebula

The Crab nebula provides exceptionally bright non-thermal emission across the entire wavelength range from radio to the most energetic photons. The spatial and spectral structure of the non-thermal synchrotron emission is known in exceptional detail. The inverse Compton emission of the nebula has just recently been spatially resolved. In this work, we reexamine the inverse Compton scattering model for the unpulsed TeV emission from the Crab Nebula. We include for the first time in detail the spatial distribution of the seed photons coming from the thermal emission. We compare the predicted spectrum with the observations including recent spectral measurements with the Fermi-LAT instrument and ground-based Cherenkov telescopes data. We will present preliminary results at the conference.

Speaker: Mrs Ludmilla Dirson (Uni of Hamburg)

137 Investigating the M31 extended gamma-ray emission from different perspectives

A new measurement of a spatially extended gamma-ray signal from the center of M31 recently reported that the emission broadly resembles the Galactic center excess (GCE) of the Milky Way (MW). In this contribution, we discuss the possibilities that the signal originates from a population of millisecond pulsars (MSPs), or alternatively the annihilation/decay of dark matter (DM) particles. An astrophysical interpretation in terms of MSPs appears viable, even after considering higher order corrections and a broad variety of uncertainties. Guided by this result, we present an analysis to derive upper limits on the annihilation cross section of weakly interacting massive particles (WIMPs) in a mass range from 1 GeV to 10 TeV, taking into account different DM density profiles and including the effect of substructure and adiabatic contraction. Furthermore, we extend the dark matter mass range of the upper (lower) limits on the DM annihilation cross section (decay lifetime) to 100 TeV in various channels by considering the results found by the HAWC collaboration.

Speaker: Mr Christopher Eckner (University of Nova Gorica)

138 Leptohadronic one-zone modelling of the blazar TXS 0506+056

The blazar TXS 0506+056, spatially consistent with the IceCube neutrino alert IC170922A, was in a flaring state during the time of the neutrino alert. Multiwavelength follow-up observations were carried out. In this contribution, the SED of TXS 0506+056 is modeled in the context of a leptohadronic one-zone model to investigate the dominant radiation mechanism during the flare. The compatibility of the observed neutrino event with the predicted neutrino flux is discussed.

139 Long-term study of TeV blazars

About fifty (Mrk 421, Mrk 501, 1ES 1959+650 and others) northern TeV extragalactic sources have been discovered during last twenty five years. Most of them (2/3) we are monitoring in Abastumani Observatory during 20 years using 125-cm and dedicated 70-cm meniscus telescopes. All observations (over 3100 nights) have been conducted with Apogee Ap6E and SBIG ST-6 CCD cameras in BVRI bands. The frames have been reduced using Daophot II and homogenous lightcurves have been constructed. The amplitudes of long-term variability are within 0.3-1.5 magnitudes. Few sources show Intra-day variability within 0.05-0.15 magnitudes, while intra-night/micro-variability is below 0.05 magnitudes. The extensive multi-wavelength campaigns with Whipple, VERITAS, HESS and MAGIC have also been conducted.

Speaker: Prof. Omar Kurtanidze (Abastumani Observatory)

140 Mass or Model! New ways to quantify the Signal Diversity in (Direct) Dark Matter Searches

Direct detection experiments are one of a few primary avenues for the potential detection of particle Dark Matter (DM). We introduce general new statistical methods to systematically study the model-discrimination power of these (and many other) instruments. In a nutshell, our approach allows one to study all possible benchmark models at once making general conclusions possible. As an application, we derive the exact boundary where near-future Xenon and Argon detectors will be (un-)able to dissect the DM-nucleon interaction and DM mass. We show that a simultaneous mass and coupling reconstruction only works in a small region of the parameter space (DM masses around 20-100 GeV) just below current detection limits. Furthermore, we show that inelastic contributions to the DM signal may further break the mass/DM-nucleon interaction degeneracy, motivating a more in depth analysis of additional signal contributions from a wider variety of models. Finally, we propose a new way to visualize the degeneracy breaking abilities of combinations of experiments, which we call Infometric Venn diagrams.

Speaker: Mr Thomas Edwards (Grappa, University of Amsterdam)

Poster ModelorMass_Euclideanized_Signals_Edwards.pdf

141 Mathematical aspects of inflationary cosmology

We show a global existence theorem for Gowdy symmetric spacetimes with a positive potential as a model for inflationary cosmology from string/M-theory. Also, asymptotic behaviour of the spacetimes is investigated. Asymptotically velocity terms dominated solutions near the initial singularity are constructed and the future asymptotic behaviour of the spacetimes is analysed. These results are support the validity of the BKL, cosmic no-hair and strong cosmic censorship conjectures.

Speaker: Prof. Makoto Narita (National Institute of Technology, Okinawa College)

142 Modeling of the spatially resolved non-thermal emission from the Vela Jr. supernova remnant

Vela Jr. (RX J0852.0−4622) is one of just a few known supernova remnants (SNRs) with a resolved shell across the whole electromagnetic spectrum from radio to very-high-energy (> 100 GeV) gamma-rays. The proximity and large size of the remnant allow for detailed spatially resolved studies of its emission and spectrum. Detection of thin bright filaments at X-ray energies places constraints on particle acceleration models and magnetic field structure in the remnant. High-resolution X-ray observations also reveal softening of the spectrum toward the interior of the remnant further constraining existing models. In this study we aim for a self-consistent radiation model of Vela Jr. which at the same time would explain the broadband emission from the source, its intensity distribution and spectral variations. We solve the full particle transport equation combined with the high-resolution 1D hydrodynamic simulations (using Pluto code) and subsequently calculate the radiation from the remnant. Equations are solved in the test particle regime. We test two models for the magnetic field profile downstream of the shock: damped magnetic field which accounts for the damping of strong magnetic turbulence downstream, and transported magnetic field. Neither of these scenarios can fully explain the observed radial dependence of the X-ray spectrum under spherical symmetry. We show, however, that the softening of the spectrum and the X-ray intensity profile can be explained under the assumption that the emission is enhanced within a cone of a limited size.

Speaker: Dr Iurii Sushch (DESY)

143 Modeling the non-thermal emission from stellar bow shocks

Since the detection of non-thermal radio emission from the bow shock of a massive runaway star simple models have predicted high-energy emission from these Galactic sources. In this work we develop a more sophisticated model for the non-thermal emission from massive run-away star bow shocks. The main goal is to establish whether these systems are efficient non-thermal emitters or they are not capable of transforming a significant amount of their power into non-thermal radiation. For modeling the collision between the stellar wind and the interstellar medium we use 2D hydrodynamic simulations. We then adopt the configuration of the wind+ambient medium obtained with the simulation as the domain for solving the transport of energetic particles injected in the system, and the non-thermal emission they produce. For this porpoise we solve a 3D advection-diffusion equation in the test-particle approximation. We find that a massive runaway star with a powerful wind deposits a considerable fraction of its total wind kinetic power as non-thermal emission, mostly produced by inverse Compton scattering of relativistic electrons with dust-emitted photons, secondly by synchrotron radiation.

Speaker: Dr Maria Victoria del Valle (Potsdam University)

Slides delValle_TeVPA.pdf

144 Multi-wavelength correlations within the SSC one-zone model for high-peaked BL Lacs

The SED of high-peaked BL Lacs is generally understood as a composition of synchrotron radiation in X-rays and self-synchrotron emission peaking at energies higher than MeV originated in one emission zone. Although most of the observations are well described by this model, orphan flares, lack of correlation between X-rays and gamma-rays and a broader SED in the gamma ray regime challenge the model. In this work, we study under which conditions it is possible to observe multi-wavelength correlations within the SSC scenario and if orphan flares are plausible.

Speakers: Dr Maria Magdalena Gonzalez (Instituto de Astronomía, UNAM), Dr Nissim Fraija (Instituto de Astronomia, UNAM)

145 Neutron star merger remnants as sources of cosmic rays below the “ankle”

We investigate non-thermal electron and nuclei energy losses within the remnant of the binary neutron star merger GW170817. We demonstrate that if the non-thermal emission originates from synchrotron radiation of a Fermi shock accelerated electron population, then the absence of a cooling break from radio to X-rays can be used to constrain the magnetic field in the remnant to the mG level. If the radiation within the source dominates over the magnetic field, the synchrotron self Compton is shown to give rise to strong gamma-ray emission. We show that VHE gamma-ray telescopes like H.E.S.S. have the necessary sensitivity to probe this process and further constrain the source's magnetic strength. We also propose an alternative scenario involving a strong magnetic field (10 G) that is able to support the observed emission. In this case, both gamma-gamma absorption and photo-disintegration of non-thermal nuclei within the remnant are efficient during the first month after the merger, and photo-meson production in the first few days. We find that this class of source is in principle able to support the population of cosmic rays detected at Earth below the ``ankle''.

Speaker: Mr Xavier Rodrigues (DESY)

Poster tevpa_poster_rodrigues.pdf

146 Numerical multi-zone leptohadronic models of gamma rays and neutrino emission by magnetic reconnection

TeV gamma-ray emission has been detected from non-blazar low luminosity active galactic nuclei (LLAGN), establishing them as potential cosmic-ray accelerators as well as sources of PeV neutrino emission. However, current observations cannot determine whether the TeV gamma rays come from the jet or from the black hole (BH) core region. In this work we consider numerical general relativitic MHD models of advection-dominated accretion flows (ADAF) around BHs where turbulent magnetic reconnection is likely to occur and accelerate cosmic rays to high energies. We use this numerical ADAF model as a background environment where we perform Monte Carlo simulations of the propagation of cosmic rays employing the CRPropa3 code. In our models we consider the interaction of cosmic rays with the magnetic, matter, and photon fields of the ADAF and obtain gamma-ray and neutrino fluxes. Based on our results, we discuss whether the detected TeV emission from non-blazar LLAGNs originated in the BH core region.

Speaker: Rafael Alves Batista (University of São Paulo)

147 On photon splitting bound on Lorentz-violating mass scale from multi-TeV photon observations

We discuss the loop-level process of photon splitting to three photons in quantum electrodynamics (QED) with broken Lorentz invariance at high energies. Concetrating to the model of standard QED with additional positive quartic term in photon dispersion relation, we calculate the rate of the process of photon splitting below the threshold of three-level process of photon decay to electron-positron pair. Although the rate of the spitting process is very small, it is very sensitive to primary photon energy, and may be compared with the rate of the photon decay at the energies of several tens TeV at the distances of several kpc or larger. Hence, photon splitting may lead to a suppression in high-energy part of spectra of known sources. Absence of such suppression in the high-energy part of spectrum of the Crab nebula is used to set lower bounds on the energy scale of Lorentz invariance violation. The bound on quartic Lorentz-violating term is better than the bound from the absence of photon decay to electron-positron pair as well as from photon timing observations, and seems to be the best in the literature. The bound would be further improved by the next generation of multi-TeV gamma-ray observatories.

Speaker: Dr Petr Satunin (INR, Moscow)

148 On the Spectra of Secondary Cosmic-Ray Nuclei Accelerated at the Supernova Remnants

Recently AMS-02 has reported the energy spectra of secondary cosmic-rays Li, Be, B up to a few TeV, which seem to be hardened above ~200GV. We discuss the production, acceleration, and escape of secondary cosmic-ray nuclei that are produced via spallation of primary cosmic-ray nuclei, such as C, N, and O in a supernova remnant (SNR) shock. Taking into account the energy-dependent escape of cosmic-ray particles from the SNR, which has been inferred from several observations, we calculated simultaneously the spectra of primary and secondary cosmic-ray nuclei escaping the SNR and running away into the interstellar medium. We show that the resulting spectra of secondary cosmic-ray nuclei would be steeper than those of primary cosmic-ray nuclei, which is contrary to the previous studies that try to explain the spectra of secondary cosmic-rays measured by PAMELA/AMS-02 by the reacceleration of secondary cosmic-rays at the SNR shock. Our results may imply that the rising of the positron fraction and the flattening of the antiproton fraction are not due to the reacceleration of secondary cosmic-rays at the SNR shock. The possibility that cosmic-ray Li nuclei are produced by a nearby Type Ia supernova following nova eruptions is also discussed.

Speaker: Dr Norita Kawanaka (Kyoto University)

149 Pair plasma generation and pulsar gamma-ray emission

Pulsars are among the most prominent gamma-ray sources observed by Fermi. Despite the wealth of observational information and considerable efforts of theorists we still do not know their exact emission mechanism(s). However, it is widely agreed upon than pulsar activity is intimately connected to the copious generation of electron-positron pairs in pulsar magnetosphere; a rapidly rotating isolated neutron star is active as a pulsar only as long as it can create pairs. The density of this pair plasma certainly affects the emission mechanism(s), wave propagation in the magnetosphere as well as emission properties of PWNe. Here I briefly overview the most recent progress in theoretical studies of pair creation in pulsar magnetospheres and report on the results of pulsar pair cascades modeling based on self-consistent numerical simulations. I discuss the implication of these results for the gamma-ray emission properties of pulsars and possible emission mechanisms responsible for pulsar gamma ray emission.

Speaker: Dr Andrey Timokhin (NASA/GSFC)

Poster poster_TeVPA_2018.pdf

150 Precision constraints on radiative neutrino decay with CMB spectral distortion

We investigate the radiative decay of the cosmic neutrino background, and its impact on the spectrum of the cosmic microwave background (CMB) that is known to be a nearly perfect black body. We derive {\it exact} formulae for the decay of a heavier neutrino into a lighter neutrino and a photon, $\nu_j \to \nu_i + \gamma$, and of absorption as its inverse, $\nu_i + \gamma \to \nu_j$, by accounting for the precise form of the neutrino momentum distribution. Our calculations show that if the neutrinos are heavier than $\mathcal O(0.1)$~eV, the exact formulae give results that differ by $\sim$50\%, compared with approximate ones where neutrinos are assumed to be at rest. We also find that spectral distortion due to absorption is more important for heavy neutrino masses (by a factor of $\sim$10 going from a neutrino mass of 0.01~eV to 0.1~eV). By analyzing the CMB spectral data measured with COBE-FIRAS, we obtain lower limits on the neutrino lifetime of $\tau_{12} > 4 \times 10^{21}$~s (95\% C.L.) for the smaller mass splitting and $\tau_{13} \sim \tau_{23} > 10^{19}$~s for the larger mass splitting. These represent up to one order of magnitude improvement over previous CMB constraints. With future CMB experiments such as PIXIE, these limits will improve by roughly 4 orders of magnitude. This translates to a projected upper limit on the neutrino magnetic moment (for certain neutrino masses and decay modes) of $\mu_\nu < 3 \times 10^{-11}\, \mu_B$, where $\mu_B$ is the Bohr magneton. Such constraints would make future precision CMB measurements competitive with lab-based constraints on neutrino magnetic moments.

Speakers: Mr Dylan van Arneman (University of Amsterdam), Mr Marnix Reemst (University of Amsterdam)

151 Primordial Anisotropies in the Gravitational Wave Background from Cosmological Phase Transitions

Phase transitions in the early universe can readily create an observable stochastic gravitational wave background. We show that such a background necessarily contains anisotropies analogous to those of the cosmic microwave background (CMB) of photons, and that these too may be within reach of proposed gravitational wave detectors. Correlations within the gravitational wave anisotropies and their cross-correlations with the CMB can provide new insights into the mechanism underlying primordial fluctuations, such as multi-field inflation, as well as reveal the existence of non-standard "hidden sectors" of particle physics in earlier eras.

Speaker: Dr Geller Michael (University of Maryland)

152 Probing the Tidal Disruption of Stars by Supermassive Black Holes with the IceCube Neutrino Observatory

Since the detection of high-energy cosmic neutrinos at the IceCube Neutrino Observatory in 2013, there has been an on-going search to find suitable transient or variable source candidates. Previous analyses testing Supernovae, GRBs and time-integrated Blazar emission have lead to constraints disfavouring these sources as dominant contributors to the observed neutrino flux. However, Tidal Disruption Events (TDEs) represent a promising untested source class. A TDE occurs when a star passes close to a Supermassive Black Hole (SMBH), and the extreme tidal forces then cause the star to disintegrate. The stellar debris is accreted onto the SMBH, and can produce highly-relativistic particle jets which significantly exceed the Eddington Luminosity that normally limits SMBH-accretion. Various models have predicted neutrino emission from both jetted and non-jetted TDEs, at levels comparable to IceCube’s sensitivity. An analysis will be presented that tests time-dependent correlation between TDEs and neutrinos, using several years of IceCube data.

Speaker: Mr Robert Stein (DESY Zeuthen)

153 Radiative Neutrino Mass via Fermion Kinetic Mixing

We propose that the radiative generation of the neutrino mass can be achieved by incorporating the kinetic mixing of fermion fields which arises radiatively at 1 loop level. As a demonstrative example of the application of the mechanism, we will present the particular case of Standard Model extension by U(1)$_D$ symmetry. As a result, we show how neutrino masses can be generated via kinetic mixing portal instead of mass matrix with residual symmetries responsible for stability of multicomponent dark matter.

Speaker: Oleg Popov (Seoul Netional University of Technology and Science)

Slides KinMix_poster_opopo001_TeVPA2018.pdf

154 Reheating neutron stars with the annihilation of self-interacting dark matter

Compact stellar objects such as neutron stars (NS) are ideal places for capturing dark matter (DM) particles. We study the effect of self-interacting DM (SIDM) captured by the nearby NS that can reheat NS to an appreciated surface temperature. Recently, DM self-interaction was considered as an negligible effect due to its small geometric cross section in NS. However, we will demonstrate when DM-nucleon cross section σχn is much smaller than the current direct search limits, DM self-interaction will dominate the capture process. As a result of small σχn, DM will not thermalize with NS and its decoupled temperature Tx(dec) is as high as a certain temperature of NS in the early evolution stage. In particular, a higher Tx(dec) will induce a larger DM thermal radius. It increases DM self-capture rate and leads to the stronger DM annihilation rate. The energy injection to NS will be more thus reheat the star. Such effect results from DM self-interaction but it behaves as DM having a relatively large σχn. The NS temperatures are produced from the interplays between DM-nucleon and DM-DM interactions. In certain parameter region, there are two possible solutions that will generate the same NS temperature. We will also show that the reheating NS surface temperature by SIDM cannot be arbitrary high. It saturates at hundreds of Kelvins depending on the DM mass. The corresponding blackbody peak wavelength is potentially detectable in the future telescopes.

Speaker: Prof. Chian-Shu Chen (Department of Physics, Tamkang University)

Poster posterTeVPA2018-1.pdf

155 Robust measurement of supernova $\nu_e$ spectra with future neutrino detectors

Measuring precise all-flavor neutrino information from a supernova is crucial for understanding the core-collapse process as well as neutrino properties. We apply a chi-squared analysis for different detector setups to explore determination of νe spectral parameters. Using a long-term two-dimensional core-collapse simulation with three time varying spectral parameters, we generate mock data to examine the capabilities of the current Super-Kamiokande detector and compare the relative improvements that gadolinium, Hyper-Kamiokande, and DUNE would have. We show that in a realistic three spectral parameter framework, the addition of gadolinium to Super-Kamiokande allows for a qualitative improvement in νe determination. Significant improvements will be made by Hyper-Kamiokande and DUNE, allowing for much more precise determination of νe spectral parameters. I am also submitting an abstract to the track Dark matter on a different topic.

Speaker: Dr Ranjan Laha (Johannes Gutenberg University Mainz)

Poster TeVPA_2018_poster.pdf

156 Science with the Southern Gamma-ray Survey Observatory (SGSO)

Fabian Schüssler on behalf of the SGSO Alliance The Southern Gamma-ray Survey Observatory (SGSO) is a proposed next-generation extensive air shower detector located at a high-altitude site in the mountains of South America. SGSO will be sensitive to astrophysical gamma rays and cosmic rays in the energy range between 100 GeV and 100 TeV. Its science case is build on three main pillars: SGSO will allow to monitor the high-energy transient sky, unveil Galactic particle acceleration at the highest energies and probe physics beyond the standard model. Recently a collection of scientists interested in the science and engineering of SGSO formed the Southern Gamma-ray Survey Observatory Alliance (sgso-alliance.org) with the aim to elucidate the expected scientific discoveries of SGSO and the design parameters required to obtain these discoveries. The Alliance currently explores several detector design options via simulations and prototyping of various elements of the detectors and assesses the suitability of possible sites for the detector deployment. This contribution will provide an overview over the science case and potential reach of SGSO. We will especially higlight expected contributions of SGSO to the era of multi-messenger time-domain astronomy at the highest energies like searches for counterparts to high-energy neutrinos and gravitational waves. We will also discuss the important synergies and complementarities with current and planned observatories like CTA.

Speaker: Dr Fabian Schussler (CEA-Saclay)

Poster SGSO_TeVPA2018_Schussler_Poster.pdf

157 Scintillator upgrade of IceTop: An extension of the IceCube surface detector array

- Thomas Huber for the IceCube-Gen2 Collaboration The IceCube Collaboration foresees to upgrade the present surface array (IceTop) with scintillation detectors. This array will be used to mitigate the impact of snow accumulation on the reconstruction of cosmic-ray showers detected by IceTop. In addition it will increase the veto capabilities for high energy astrophysical and cosmogenic neutrinos of IceCube. Furthermore, it will serve as a R&D program for a possible future large-scale surface array. Two prototype stations with 7 scintillation detectors each showcasing technological advances have been developed and were deployed at the South Pole in January 2018. Each scintillation detector features 1.5 m² of plastic scintillators and wavelength-shifting fibers which are read out by Silicon Photomultipliers. The detector design, the operation status, first measurements and prospects of the upgrade will be presented in this contribution. In addition, the science case of the array will be discussed.

Speaker: Mr Thomas Huber (Herr)

158 Search for PeV photons associated with IceCube neutrino events: Carpet-2 first results and Carpet-3 prospects

Carpet is an air-shower array at Baksan, Russia, equipped with a large-area muon detector, which makes it possible to separate primary photons from hadrons. We report first results of the search for primary photons with energies E>1 PeV, associated with IceCube neutrino flux, in the data obtained with Carpet-2 (175 square-meter muon detector). The installation was upgraded to Carpet-3 (410 square-meter muon detector) in 2018. The sensitivity of the upgraded experiment to E>100 TeV photons is also discussed.

Speaker: Prof. Sergey Troitsky (INR, Moscow)

Poster poster.pdf

159 Search for ultra-high energy photons through preshower effect: study of CTA-La Palma efficiency'

As gamma rays propagate from their sources of production to Earth, radiation-matter interactions can occur, leading to an effective screening of the incident flux. In the PeV-EeV range, the dominant energy loss mechanism for photons is the production of electron-positron pairs. These pairs can emit bremsstrahlung photons as they interact with local electromagnetic fields. These photons can initiate air showers in the Earth atmosphere that gamma-ray telescopes can detect through the emission of Cherenkov radiation. The Cosmic-Ray Extremely Distributed Observatory has taken on the challenging goal to detect such correlated air showers in the hope to open a new observation channel on the Universe. Here, we discuss the preliminary results of multivariate analysis used to discriminate between air showers generated by photon ensembles from air showers produced by cosmic-ray background, taking the example of the next-generation gamma-ray observatory Cherenkov Telescope Array (CTA) in La Palma.

Speaker: Mr Kevin Almeida Cheminant (Institute of Nuclear Physics Polish Academy of Science)

160 Search of very high energy emission from GRBs with HAWC

Gamma-ray bursts (GRBs) are one of the most captivating extragalactic astrophysical phenomena. These transient events have been widely proposed as bright sources of the most energetic cosmic rays and gravitational waves. With its wide field of view (~2 str) and >95% duty cycle, the High Altitude Water Cherenkov (HAWC) Observatory, installed at 4100 m a.s.l. in the state of Puebla (Mexico), is the optimal instrument to search for VHE photons (> 100 GeV) from GRBs. We report results obtained from the analysis of a sample of GRBs detected by satellite instruments in the field of view of HAWC. We particularly discuss the case of GRB 170817A/GW 170817 that is associated to the first common detection of gravitational waves and multi-messenger observations of a merger of two neutron stars. We describe different search approaches currently used by HAWC, an all-sky search method as well as a real-time analysis of GRBs triggered by satellites. Results and physical implications are discussed in the framework of current GRB models.

Speakers: Dr Maria Magdalena González Sánchez (Universidad Nacional Autónoma de México - Instituto de Astronomía), Dr Nissim Illich Fraija Cabrera (Universidad Nacional Autónoma de México - Instituto de Astronomía), Dr Simone Dichiara (Universidad Nacional Autónoma de México)

Poster TeVPA_HAWC_GRB_poster_v3.pdf

161 Searching for TeV Halos in a HAWC Stack

Recent work has suggested that spatially extended TeV emission from pulsars (TeV Halos), such as that seen corresponding to Geminga, Monogem, and HAWC J0543+233 is distinct from Pulsar Wind Nebulae seen in X-ray energies. The primary difference between the two is one of particle transport; for a PWN leptons are confined near the pulsar due to interactions between the pulsar wind and the surrounding medium, whereas for a TeV Halo the extent of the observed gamma-ray emission is limited by diffusion. Because this emission is expected to be isotropic, this opens the window to the discovery of invisible pulsars, in which the pulsed emission seen at other wavelengths is not aimed at the Earth. This presentation will focus on current efforts to characterize the population of TeV Halos in HAWC observations, which may constitute up to 40% of the sources in the dataset. Investigating the possibility of TeV Halos around young and millisecond pulsars will be discussed. Characterizing the TeV Halos for known pulsars is critical to discovering an as yet unseen source class of invisible pulsars.

Speaker: Mr Chad Brisbois (Michigan Technological University)

Poster TeVPA_POSTER_2018_(2).pdf

162 SENSE - Ultimate Low Light-Level Sensor Development

SENSE - Ultimate low light-level sensor development is a project funded by the EC Horizon 2020 as FET Open Coordination and Support Action (CSA). The aim of SENSE is to coordinate research and development efforts in academia and industry in low light-level (LLL) sensoring. Therefor we prepared a European R&D roadmap towards the ultimate LLL sensor and with the experts group the progress with respect to the roadmap will be monitored. In collaboration with several labs, experienced in measuring photosensors, a common characterization of SiPMs with standardized measurements and analysis procedures is developed. Further cooperation especially with industrial partners is in preparation. Another main aspect of the project is the dissemination of results and the communication between all involved partners and interested parties. The SENSE website, including the SENSE forum, provides all kind of information related to photosensors and allows for communication between all involved actors. In the future a database containing the results of SiPM characterization is planned. Several outreach activities and special trainings for students are also part of the project and will be extended in the future. The consortium has four partners: DESY (Coordinator), Germany; UNIGE, Switzerland; MPP, Germany and KIT, Germany. Several international experts on all parts of LLL developments are involved in the expert or working group of the project.

Speaker: Katrin Link (KIT)

163 SModelS - Development towards signatures beyond missing energy

SModelS is a tool designed to decompose Beyond Standard Model (BSM) theories with a Z2 symmetry and confront them to results from the LHC experiment. The code uses simplified models results to achieve the task in a model independent way. The existing version focuses on supersymmetry searches with missing energy (MET) final state and already includes a large variety of searches from ATLAS and CMS. Ongoing development is aimed at exploring beyond MET signatures of current interest within the theory and experimental community. I will present the latest SModelS development which includes upgrading SModelS to a completely object oriented version and thus allows to probe beyond BSM models containing non-MET signatures. The modification facilitates integrating the particles’ properties such as mass and life time which is imperative to investigate other signatures. Furthermore, I will present the improved database of experimental results which is extended by adding the latest results from the LHC including searches for Heavy Stable Charged Particles (HSCP). On the basis of these developments I will exemplify the impact of this new SModelS version on new physics scenarios.

Speaker: Alicia Wongel (HEPHY)

164 Status of the AMEGO Subsystem Development

The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe-class mission concept designed to operate at energies from $\sim$ 200 keV to > 10 GeV. Both Compton scattering and pair-production events must be considered in the AMEGO design since the interaction cross section has a crossover at $\sim$ 15 MeV. AMEGO is made of four major subsystems: a plastic anticoincidence detector for rejecting cosmic-ray events, a silicon tracker for measuring the energies of Compton scattered electrons and pair-production products, a CZT calorimeter for measuring the energy and location of Compton scattered photons, and a CsI calorimeter for measuring the energy of the pair-production products at high energies. The prototype subsystems are under development at the NASA Goddard Space Flight Center and the Naval Research Laboratory; in this contribution we provide details on the development of the different subsystems in preparation for beam tests and a balloon flight.

165 Strongly interacting dark matter cannot explain DAMA

The main strategy of dark matter (DM) direct searches is to look for nuclear recoils from DM particles scattering on the detector medium. Of all the existing DM direct detection experiments only the DAMA experiment claims to observe the characteristic annually oscillating DM signal with the right phase at the significance level of ~ 12 sigma. Since many other experiments using various methods and having, in principle, better sensitivity to nuclear recoils detect nothing and put severe constraints on the DM mass and cross section, the conventional interpretation of the DAMA results, i.e. weakly interacting DM scattering on nuclei, becomes questionable. One of the possible explanations is related to the model of DM which interacts strongly with the ordinary matter. Given some assumptions about the peculiar features of DM interaction one can expect the signal in DAMA and the absence of any signal in other existing detectors. I am going to show why such kind of models fails to reproduce the DAMA signal.

Speaker: Maxim Laletin (ULiege)

166 Sudakov log resummation for indirect detection of heavy WIMP dark matter

In some models for WIMP dark matter, radiative corrections dominate over the LO contributions in the computation of annihilation cross sections relevant for indirect detection. These corrections need to be resummed to all orders in perturbation theory for theoretical predictions to be sensible. In this talk I will employ -and briefly review- resummation methods that are traditionally used in other contexts (colliders, etc.) in order to mitigate those large radiative corrections that, on top of the Sommerfeld effect, are encountered in the phenomenology of heavy DM models. Although most of the discussion can be applied to a larger family of models and detection channels, I will focus on the pure wino model and the spectral gamma-ray line feature. More specifically, we use the soft collinear effective theory (SCET) approach to resum the large Sudakov corrections (at NLL' accuracy) for the computation of the semi-inclusive photon energy spectrum in χ0χ0→γ+X in the vicinity of the maximal photon energy Eγ=mχ. Results and phenomenological aspects in light of the CTA gamma-ray telescope will of course be also presented and discussed.

Speaker: Mr Martin Vollmann (Technical University of Munich)

167 TeV gamma and Cr anisotropy partially correlated to UHECR map?

The Uhecr anisotropy at tens EeV and at 60 EeV found by Auger maps overlap partially with the observed TeV anisotropy found by Argo and Hawc array detectors lastt decade. We had proposed it since many years. These combined signals offer a reading key to identify the Uhecr source names, their address and their secondary fragment tails.

Speaker: Dr Daniele Fargion (Physics Depart., ROME UNIVERSITY 1 and INFN)

168 TeV particles in protostellar jets

Supersonic and collimated bipolar jets are launched from the inner regions of accretion discs in forming stars. Jets from young stellar objects are well known thermal emitters. However, non-thermal radio emission from a handful of protostellar jets has been reported in the last years. The detection of synchrotron radiation indicates the presence of relativistic electrons and magnetic fields of about 0.1 mG. Protons can be accelerated as well. Below certain conditions, non-resonant hybrid (Bell) instabilities can be excited by the streaming of protons being accelerated and the magnetic field is amplified. We study diffusive shock acceleration and magnetic field amplification in protostellar jets with velocities ~500 km/s. The maximum energy that electrons and protons can achieve is constrained by escape and radiative losses, as well as damping of scattering waves, where the ionization of the plasma plays an important role. We find that both electrons and protons can be accelerated up the TeV domain and therefore emit gamma rays in their interaction with photon and matter fields. The detection of this radiation by the forthcoming Cherenkov Telescope Array will open a new window to study the formation of massive stars, as well as diffusive acceleration and magnetic field amplification in astrophysical shocks with velocities of about 500 km/s.

Speaker: Dr Anabella Araudo (Astronomical Institute of the Czech Academy of Sciences)

169 TeV-candidate extreme blazars among Swift-BAT sources

Blazars spectral energy distributions are dominated by non-thermal emission from the jet, consisting of two main bumps. For the so-called extreme blazars, these components each peak in the X-ray and GeV-TeV bands. Recent TeV observations have revealed a few of these objects whose second peak exceeds several TeV (e.g. 1ES 0229+200). Such intriguing sources have been objects of different studies regarding the contribution of lepto-hadronic processes to their emission mechanism, the possible origin of extragalactic high-energy neutrinos, the implications of their TeV spectra on the extragalactic background light indirect estimates, and the intergalactic magnetic field measurements. In order to increase the number of TeV EHBLs, we developed a criterium in order to select good EHBL candidates. Our sample is composed of six EHBL detected both in the hard X-ray band by the Swift-BAT telescope and in the high-energy band by the Fermi-LAT telescope, each of them not yet detected in the TeV band. We provide a multi-band study of their spectral energy distribution, discussing their potential detectability by the current and next generations of TeV gamma-ray telescopes.

Speaker: Dr Luca Foffano (University of Padova)

Poster TevPA2018_BATpaper_reduced.pdf

170 The experimental complex for complementary investigations of inclined EAS generated in cosmic ray nuclear interactions

Experimental complex NEVOD for investigations of cosmic rays in the energy interval (10^15-10^19 eV) is described. The composition of primary cosmic rays in the high energy region becomes heavier and interactions of these cosmic rays are nucleus-nucleus. The complex consists of Cherenkov water detector with 2000 m^3 volume, coordinate-tracking detector DECOR with 70 m^2 area, array of scintillator detectors forming calibration telescopes system (CTS) and array of thermal neutron detectors PRISMA. Nowadays, NEVOD is being expanded with three new setups: NEVOD-EAS of 10^5 m^2 for determination of air shower axis, URAN for registration of neutrons in EAS, and coordinate-tracking detector TREK on drift chambers of 250 m^2 effective area. The first part of new detectors in now under operation. Examples of detection of the first events by means of the combined array are discussed.

Speaker: Dr Egor Zadeba (MEPhI)

171 The IceCube enhanced starting track event selection and realtime stream

IceCube analyses which look for an astrophysical neutrino signal in the southern sky face a large background of atmospheric muons and neutrinos created in cosmic ray air showers. Selecting for events which start inside the detector suppresses not only the downgoing muon background, but also the southern sky atmospheric neutrino background by the energy- and declination-dependent atmospheric self-veto effect. By using the good pointing resolution found with muon tracks, this selection determines a veto region before the starting vertex for each event and calculates the likelihood for not observing a hit on the IceCube optical modules in the veto region. This starting track event selection has a high astrophysical neutrino purity above 10 TeV in the southern sky. We will present on the advantages of this event selection for neutrino point source searches and diffuse flux searches and provide a first look at the realtime event stream derived from the selection.

Speaker: Sarah Mancina (University of Wisconsin - Madison)

172 The Impact on Dark Matter Abundances from an Early Kinetic Decoupling

The standard way to calculate the thermal relic abundance of dark matter relies on the assumption that the dark matter particles remain in kinetic equilibrium throughout the chemical freeze-out process. However, this assumption is not always justified. This talk aims to address how to handle such situations, i.e. when an early kinetic decoupling happens, and discuss the phenomenological consequences. Two approaches are explored: One that combines higher momentum moments of the underlying Boltzmann equation and the other is to numerically find the evolution of the full phase-space distribution of the dark matter particles. The implications are illustrated for the case of the Scalar Singlet model, which is often referred to as the simplest WIMP model. In this model, it can be explicitly shown that the predictions of the dark matter abundance can be altered by up to an order of magnitude.

Speaker: Dr Michael Gustafsson (Göttingen University)

173 Truncation of AGN jets by their interaction with an stellar cluster

We study the effects of interaction of jets in Active Galactic Nuclei when they encounter stellar clusters passing across the inner jet. The interaction provides a scenario to address non–thermal processes. In jet–star interactions a double bow–shock structure is formed where particles get accelerated via diffusive mechanism. Individual encounters have a limited effect, however, dense clusters of massive stars can truncate the jet as the cluster crosses the jet line near the jet launching region. A bow shock is formed by the interaction of the cluster collective wind with the jet. Much of the jet kinetic energy density is transferred to the shock and becomes available to accelerate particles. The interaction of jets with clusters of massive stars is a promising scenario to explain the gamma ray emission from radiogalaxy jets.

Speaker: Dr Anabella Araudo (Astronomical Institute of the Czech Academy of Sciences)

174 Velocity dependent dark matter constraints from conversion of cross section in EFT.

The supersymmetric WIMP hypothesis is currently under scrutiny as there is no experimental result supporting the existence a lightest supersymmetric particle. The recent non-detection in large scale direct detection experiments has demonstrated that a broader approach towards dark matter particles is indicated. In this work, we show a simple approach to convert constraints/sensitivities from direct detection experiments into indirect constraints (and vice versa). This helps to use the complementary information provided by different dark matter search methods in a consistent way. Furthermore, the same approach is then useful to calculate the corresponding relic density under the assumption of thermal dark matter production.

Speaker: Mr Chao Zhang (IEXP/Univ.Hamburg)

175 X-ray/gamma-ray flux correlations in the BL Lac Mrk 421 using HAWC data

The HAWC gamma ray observatory is located at the Sierra Negra Volcano in Puebla, Mexico, at an altitude of 4,100 meters. HAWC is a wide field of view array of 300 water Cherenkov detectors that are continuously surveying ~ 2sr of the sky, operating since March 2015. The large collected data sample allows HAWC to perform an unbiased monitoring of blazars. One of the closest and brightest blazar in the gamma-ray/X-ray sky, Mrk 421, classified as high-synchrotron-peaked BL Lac class, has extensively monitored by the Large Area Telescope on-board the Fermi satellite, and the BAT and XRT instruments of the Swift satellite. In this work, we use more than 3 years of HAWC data together with Swift-XRT data to characterize potential correlations between both bands. This analysis shows that HAWC and Swift-XRT data are correlated even stronger than expected for quasi-simultaneous observations. This result favors the one-zone synchrotron self-Compton model

Speaker: Dr Jose Andres Garcia-Gonzalez (IF-UNAM)

Cosmic Rays: 3

Chair 1: Don Ellison | Chair 2: Denise Boncioli | Chair 3: Andrew Taylor | Chair 4: Daniele Gaggero |
Chair 5: Tony Bell | Chair 6: Markus Ahlers

Conveners: Andrei Bykov (Ioffe Physico-Technical Institute), Dr Sabrina Casanova (IFJ PAN &amp; MPIK HD), Dr denise boncioli (DESY)

176 Data-driven model of the cosmic-ray flux and mass composition over all energies

We present a new parametrisation of the cosmic-ray flux and its mass composition over an energy range from 1 GeV to 10^11 GeV. We combine measurements of the flux of individual elements from high-precision satellites and balloon experiments with indirect measurements of mass groups from the leading air shower experiments. We provide the first fit of this kind that consistently takes both statistical and systematic uncertainties into account. The uncertainty on the energy scales of individual experiments is handled explicitly in our mathematical approach. We obtain a common energy scale and adjustment factors for the energy scales of the participating experiments. Our fit has a reduced chi2 value of 1, showing that experimental data are in good agreement, if systematic uncertainties are taken into account. Our model may serve as a world-average of the measured fluxes for individual elements from proton to iron from 1 GeV to 10^11 GeV. It is useful as an input for simulations or theoretical computations based on cosmic rays. The experimental uncertainties of the input data are captured in a covariance matrix, which can be propagated into derived quantities.

Speaker: Dr Hans Dembinski (MPIK Heidelberg)

Slides dembinski_gsf.pdf

177 UHECR propagation and interpretation of UHECR data

Charged particles of extraterrestial origin with energies in excess of 10¹⁸ eV (known as ultra-high-energy cosmic rays, UHECR) were first observed in the 1960s, and current-generation UHECR detectors have collected over 10⁵ such events. Nevertheless, the interpretation of these data is not straightforward, and the sources of such particles are still unknown (but widely believed to be extragalactic). Complications include interactions of these particles with cosmic background photons, deflections of their trajectiories by magnetic fields, and the large systematic uncertainties and model-dependence of current determinations of their mass composition. In my talk, I summarize the state of the art in UHECR research, the main obstacles to answering currently open questions, and the outlook for the near future.

Speaker: Dr Armando di Matteo (ULB)

Slides slides.pdf

178 Low-luminosity gamma-ray bursts as the sources of ultrahigh-energy cosmic ray nuclei

Recent results from the Pierre Auger Collaboration have shown that the composition of ultrahigh- energy cosmic rays (UHECRs) becomes gradually heavier with increasing energy. Although gamma- ray bursts (GRBs) have been promising sources of UHECRs, it is still unclear whether they can account for the Auger results because of their unknown nuclear composition of ejected UHECRs. In this work, we revisit the possibility that low-luminosity GRBs (LL GRBs) act as the sources of UHECR nuclei, and give new predictions based on the intrajet nuclear composition models considering progenitor dependencies. We find that the nuclear component in the jet can be divided into two groups according to the mass fraction of silicon nuclei, Si-free and Si-rich. Motivated by the connection between LL GRBs and transrelativistic supernovae, we also consider the hypernova ejecta composition. Then, we discuss the survivability of UHECR nuclei in the jet base and internal shocks of the jets, and show that it is easier for nuclei to survive for typical LL GRBs. Finally, we numerically propagate UHECR nuclei ejected from LL GRBs with different composition models and compare the resulting spectra and composition to Auger data. Our results show that both the Si- rich progenitor and hypernova ejecta models match the Auger data well, while the Si-free progenitor models have more difficulty in fitting the spectrum. We argue that our model is consistent with the newly reported cross correlation between the UHECRs and starburst galaxies, since both LL GRBs and hypernovae are expected to be tracers of the star-formation activity. LL GRBs have also been suggested as the dominant origin of IceCube neutrinos in the PeV range, and the LL GRB origin of UHECRs can be critically tested by near-future multimessenger observations.

Speaker: Mr Bing Theodore Zhang (Peking University)

Slides TeVPA2018_zhang_v2.pdf

179 Ultra-High-Energy Cosmic Rays and Neutrinos from Tidal Disruptions by Massive Black Holes

In addition to the emergence of time domain astronomy, the advent of multi-messenger astronomy opens up a new window on transient high-energy sources. Through the multi-messenger study of the most energetic objects in our universe, two fundamental questions can be addressed: what are the sources of ultra-high energy cosmic rays (UHECRs) and the sources of very-high energy neutrinos? Jetted Tidal Disruption Events (TDEs) appear as interesting candidate sources of UHECRs, with their impressive energy reservoir and estimated occurrence rates. By modeling and simulating the propagation and interaction of UHECRs in various types of radiative backgrounds, we can evaluate the signatures of TDEs powering jets in UHECRs and neutrinos. We find that we can reproduce the latest UHECR spectrum and composition results of the Auger experiment for a range of reasonable parameters. The diffuse neutrino flux associated with this scenario is found to be subdominant, but nearby events could be detected by IceCube or next-generation detectors such as IceCube-Gen2.

Speaker: Ms Claire Guépin (Institut d'Astrophysique de Paris)

Slides TeVPA_2018_CG_CRs.pdf

180 Tidally disrupted stars as a possible common origin of cosmic rays and neutrinos at the highest energies

The origin of ultra-high energy cosmic rays (UHECRs) is still one of the biggest unsolved questions in astrophysics. We present a novel approach combining the knowledge about neutrinos and cosmic rays at the highest energies to give an alternative, joint solution to this question with Tidal Disruption Events (TDEs). TDEs are processes where stars are torn apart by the strong gravitational force close to a massive or super-massive black hole. Some of these objects happen to launch a relativistic jet, where particles may be accelerated in internal shocks. We simulate the photo-hadronic interactions in the TDE jet as well as in the propagation through extra-galactic space in a combined source-propagation model, which is a key novelty of our work beyond the state-of-the-art. We demonstrate that it is possible to fit the UHECR spectrum and composition and describe PeV neutrino data simultaneously if a nuclear cascade develops in the source. Out of the fit procedure we obtain the necessary abundance and power of such events in order to draw a self-consistent picture, which is compatible with current constraints and which is testable by further observations.

Speaker: Daniel Biehl (DESY Zeuthen)

Slides 180828_TDE-Biehl.pdf

181 Ultra-High-Energy Cosmic Rays from Radio Galaxies

Radio galaxies are intensively discussed as the sources of cosmic rays observed above about 3 EeV, called ultra-high energy cosmic rays (UHECRs). The talk presents a first, systematic study that takes the individual characteristics of these sources into account, as well as the impact of the galactic magnetic field, as well as the extragalactic magnetic-field structures up to a distance of 120 Mpc. It will be shown that the average contribution of radio galaxies taken over a very large volume cannot explain the observed features of UHECRs measured at Earth, but could provide an explanation of the CRs with energies of a few EeV. However, a very good agreement with the spectrum, composition, and arrival-direction distribution of UHECRs measured by the Pierre Auger Observatory (Auger) is obtained by the contribution from only a few ultra-luminous ones, in particular Cygnus A and Centaurus A. Cygnus A needs to provide a mostly light composition of nuclear species dominating up to about 60 EeV, whereas the nearest radio galaxy, Centaurus A, provides a heavy composition and starts to dominate above 60 EeV. Thus, this scenario most likely also predicts differences in UHECR spectrum and composition between the northern and southern hemispheres. In order to account for these differences we include the geometrical exposure effects of Auger and the Telescope Array Observatory, which even improves the aggreement to the their measurements.

Speaker: Dr Björn Eichmann (Ruhr-Universität Bochum, Theoretische Physik IV)

Slides Eichmann__UHECRs_from_RGs.pdf

Gamma Rays: 3

Chair 1: Stefan Ohm | Chair 2: Ruben Lopez-Coto | Chair 3: Sara Buson | Chair 4: Felicia Krauss | Chair 5: Francesco Longo | Chair 6: David Sanchez | Chair 7: Konstancja Satalecka

Conveners: Dr Ruben Lopez-Coto (INFN Padova), Dr Sara Buson (NASA-GSFC), Mr Stefan Ohm (DESY, Zeuthen)

182 Gamma-ray emission from massive star clusters

We report the detection of diffuse gamma-ray emissions towards several massive star clusters in our Galaxy. The detailed spectral and spatial analysis reveal a remarkable constancy of the energy and radial distribution of the cosmic ray density, w(E; r) ~ E^2.3 r^{-1} around these massive star clusters. The 1/r decrement of the CR density with the distance from the star cluster is a distinct signature of continuous injection of CRs and their diffusion through ISM. The analysis of gamma-ray data show that the hard energy spectra of parent protons continue up to 1 PeV. The results imply that the population of young massive stars can provide a substantial fraction of Galactic cosmic rays and are potential candidates of Galactic PeVatrons.

Speaker: Dr Ruizhi Yang (Max-Planck-Institut für Kernphysik)

Slides ruizhi_tevpa.pdf

183 Observation of Galactic gamma-ray sources above 100 TeV with the HAWC Observatory

Since Galactic cosmic rays are observed in the PeV range, at least a few sources that accelerate particles to this energy (“PeVatrons”) should exist. A PeVatron is expected to have a hard, hadronic gamma-ray spectrum that extends to at least tens of TeV without any apparent spectral break or cutoff. High energy (> 100 TeV) gamma ray observations are therefore essential to the study of these cosmic accelerators. Additionally, any leptonic component of the gamma-ray emission is suppressed at these energies. The High Altitude Water Cherenkov Observatory (HAWC) has sensitivity to gamma rays in this largely unexplored energy range and is well poised to perform all-sky surveys due to its high duty cycle and large field-of-view. I will discuss sources seen above 100 TeV in the first 1000 days of HAWC data and discuss whether any of them can be identified as PeVatron candidates. As PeVatrons are also expected to emit neutrinos, I will also briefly discuss connections to the IceCube astrophysical neutrinos.

Speaker: Mr Chad Brisbois (Michigan Technological University)

Slides 2018TeVPA-100TeV.pdf

184 Three-dimensional models of the interstellar medium for the propagation of cosmic rays and their non-thermal interstellar emissions

High-energy gamma rays of interstellar origin are produced by the interaction of cosmic-ray (CR) particles with the diffuse gas and radiation fields in the Galaxy. The main features of this emission are well-understood and are reproduced by existing CR propagation models employing 2D Galactocentric cylindrically symmetrical geometry. However, the high-quality data from instruments like the Fermi Large Area Telescope reveal significant deviations from the model predictions on few to tens of degree scales indicating the need to include the details of the Galactic spiral structure and thus require 3D spatial modelling. In this contribution the propagation of CRs and generation of high-energy interstellar emissions from the Galaxy are calculated using the latest release of the GALPROP code employing 3D spatial models for the CR source, interstellar gas, and interstellar radiation field (ISRF) densities. The interstellar emission models that include arms and bulges for the CR source and ISRF densities provide plausible physical interpretations for features found in the residual maps from high-energy gamma-ray data analysis. The 3D models for the CR and interstellar medium densities provide a more realistic basis for interpretation of the direct CR measurements and for their non-thermal interstellar emissions including the directions toward the inner Galaxy and about the Galactic centre.

Speaker: Dr Troy Porter (Stanford University)

Slides galprop3d.pdf

185 Modeling the non-thermal emission from stellar bow shocks

Since the detection of non-thermal radio emission from the bow shock of a massive runaway star simple models have predicted high-energy emission from these Galactic sources. In this work we develop a more sophisticated model for the non-thermal emission from massive run-away star bow shocks. The main goal is to establish whether these systems are efficient non-thermal emitters or they are not capable of transforming a significant amount of their power into non-thermal radiation. For modeling the collision between the stellar wind and the interstellar medium we use 2D hydrodynamic simulations. We then adopt the configuration of the wind+ambient medium obtained with the simulation as the domain for solving the transport of energetic particles injected in the system, and the non-thermal emission they produce. For this porpoise we solve a 3D advection-diffusion equation in the test-particle approximation. We find that a massive runaway star with a powerful wind deposits a considerable fraction of its total wind kinetic power as non-thermal emission, mostly produced by inverse Compton scattering of relativistic electrons with dust-emitted photons, secondly by synchrotron radiation.

Speaker: Dr Maria Victoria del Valle (Potsdam University)

Slides delValle_TeVPA.pdf

186 H.E.S.S. observations of the Small Magellanic Cloud

The Small Magellanic Cloud is the second-nearest star-forming galaxy to our Milky Way at a distance of about 60 kpc with major star-formation episodes at 6 Gyr, 0.7 Gyr and 10 Myr ago. This makes the Small Magellanic Cloud an ideal target to study objects related to young stellar populations over a wide range of age. The Magellanic Clouds are currently the only galaxies for which individual sources and large-scale emission can be resolved by ground-based Cherenkov telescopes. Therefore, they offer the unique possibility to study the connection of the Galactic population of VHE gamma-ray sources and the "integrated" diffuse emission seen from e.g other star-forming galaxies. In the last years extensive surveys of the Magellanic Clouds were performed with the H.E.S.S. telescopes resulting in an energy flux sensitivity comparable to the brightest TeV gamma-ray sources in the Milky Way. This allows us to compare the TeV source populations in the Milky Way, the Large Magellanic Cloud and the Small Magellanic Cloud. In this contribution I will show, for the first time, the results for the H.E.S.S. survey of the Small Magellanic Cloud. I will discuss potential gamma-ray source populations, which include supernova remnants, pulsars, pulsar wind nebulae, high-mass X-ray binaries and star forming regions, and compare them to those of the Milky Way and known sources in the Large Magellanic Cloud. Finally, I will discuss similarities and differences of particle acceleration processes in the three systems and the importance of the environment for the efficiency of gamma-ray production.

Speaker: Ms Maria Haupt (DESY)

Slides SMC_TeVPA-2018-08_v2.pdf

187 The Disconnect Between Radio and Gamma-Ray Emission in Arp 220

Recent analyses of the gamma-ray flux from Arp 220 have shown that the observed gamma-ray flux is larger than can be accounted for by the measured star formation rate. In contrast, the radio spectra observed for the galaxy's two nuclei are consisted with the observed rate. This indicates an excess of cosmic rays or additional cosmic ray population which produces more gamma-ray emission but not more radio emission. Investigating potential resolutions to this disconnect between the radio and gamma-rays, we find that an optical depth (for infrared emission) greater than unity allows for an increase in the cosmic ray energy injection rate to increase the gamma-ray emission without also increasing the radio emission. Further, our results are consistent with estimates of optical depths at millimeter and submillimeter wavelengths.

Speaker: Tova Yoast-Hull (Canadian Institute for Theoretical Astrophysics)

Slides YoastHull_TeVPA2018.pdf

Gravitational Waves: 1

Chair 1: Daniel Kocevski | Chair 2: Harald Pfeiffer

Conveners: Daniel Kocevski (NASA/MSFC), Dr Harald Pfeiffer (Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute)), Samaya Nissanke (GRAPPA, University of Amsterdam)

188 Gamma-ray emission from GRB 170817

Follows soon.

Speaker: Mr Eric Burns (NASA)

Slides 1645_Eric_Burns.pptx

189 The importance of the cocoon emission in double Neutron star mergers

Following a Neutron star merger a jet propagates and interacts with the out owing ejecta that surrounds the merger. As a result matter is pushed around the jet to form a hot cocoon which applies pressure on the jet and potentially collimates it. The cocoon envelops the jet as long as the jet propagates within the dense ejecta. After the jet breaks out, the cocoon expands and emits radiation over large angles throughout the entire electromagnetic spectrum, from Gamma-rays to radio. In GW170817 the cocoon is a leading candidate to be the source of the observed Gamma-ray emission and dominated the frst appr. 2 months of the afterglow emission, until the jet decelerated enough to become visible. Likewise, observations of future double NS merger events are also expected to be dominated by the cocoon emission due to the beaming of the jet emission. Furthermore, it is possible that some jets are choked inside the ejecta, in which cases the cocoon becomes the leading candidate to produce the entire prompt and afterglow emissions. In this talk I will present the different mechanisms of emission from the cocoon and discuss what we can learn about the GW170817 system from observations. I will end with what it tells us about future double Neutron star merger detections. Ore Gottlieb(1), Ehud Nakar (1), Tsvi Piran (2) (1) The Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel (2) Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel

Speaker: Mr Ore Gottlieb (Tel Aviv Univesity)

Slides Ore_Gottlieb.pptx

190 An r-Process Kilonova Associated With The Gravitational Wave Event GW170817

Follows soon.

Speaker: Dr Philip Cowperthwaite (Carnegie Observatories)

Slides pcowpert_TeVPA2018.pdf

191 A Multimessenger Picture of Binary Neutron Star Mergers

With the detection of the binary neutron star merger GW170817 a new era of multi-messenger astronomy started. GW170817 proved that neutron star mergers are ideal laboratories to constrain the equation of state of cold supranuclear matter, to study the central engines of short GRBs, and to understand the origin and production of heavy elements. In this talk, we discuss how the last milliseconds before and after the merger can be studied with full 3D numerical relativity simulations to obtain information about the emitted gravitational wave and electromagnetic signals.

Speaker: Dr Tim Dietrich (Nikhef (Dutch National Institute for Subatomic Physics))

Slides Berlin.pptx

192 Probing nuclear physics with gravitational waves

The gravitational waves from a neutron star binary inspiral carry unique information about fundamental physics in extreme conditions. I will discuss the imprints of the properties of neutron star matter on the gravitational waves, what we have learned from the neutron star binary inspiral event GW170817, and outline future prospects and challenges.

Speaker: Dr Tanja Hinderer (Radboud University Nijmegen)

Slides TeVPA2018.pdf

193 The long vision of gravitational wave astronomy

Recent gravitational wave (GW) detections with LIGO/Virgo opened a new window on the Universe, unveiling the most violent catastrophic events in the cosmos. GW astronomy is just in its infancy, the Laser Interferometer Space Antenna (LISA) and Pulsar Timing Arrays (PTAs) will offer a complementary view of the GW universe in a much more extended range of frequencies, from mHz down to nHz. I will discuss the status and science objectives of LISA and PTA, their targeted sources and the science they will enable in the future decades.

Speaker: Dr Alberto Sesana (University of Birmingham)

Slides Sesana_TeVPA18.pdf

Neutrino Astronomy: 3

Chair 1: Fabrizio Tavecchio | Chair 2: Andrea Palladino | Chair 3: Francesco Villante | Chair 4: Joshua Wood | Chair 5: Summer Blot | Chair 6: Markus Ahlers

Conveners: Dr Aart Heijboer (NIKHEF), Dr Andrea Palladino (DESY), Claudio Kopper (University of Alberta)

194 Recent results from the ANTARES neutrino telescope

The discovery of a cosmic neutrinos diffuse flux by IceCube together with the recent observation of gravitational waves have widened our spectrum of probes needed for multi-messenger astronomy. However, the origin of the faint flux of high-energy astrophysical neutrinos is still unknown. The ANTARES neutrino telescope is currently the detector with the largest sensitivity located in the Northern hemisphere, optimised to detect neutrinos in the TeV/PeV range. It is located in the Mediterranean Sea at a water depth of about 2500 m, 42 km from Toulon, France. The direct view of the Southern sky provides a complementary field of view to the IceCube observatory with good low-energy sensitivity. The excellent angular resolution for both track and cascade events allows for powerful all-flavour analyses. Recent results obtained with ANTARES data will be presented, focusing on the measurement of the diffuse flux and probing the IceCube high energy neutrino directions, as well as recent multi-messenger observations. The results and prospects of dark matter searches will be also shown and the measurement of neutrino oscillations together with constraints on the 3+1 sterile neutrino model will be discussed.

Speaker: Dr Simone Biagi (INFN - Laboratori Nazionali del Sud)

Slides Talk_Biagi_ANTARES.pdf

195 Searching for Ultra-High Energy Neutrinos with ANITA

ANITA (the ANtarctic Impulsive Transient Antenna) is a long-duration balloon borne radio interferometer designed to search for ultra-high energy (> 10^18 eV) cosmogenic neutrinos. Over a few weeks it flies at an altitude of 37km, scanning the Antarctic ice for Askaryan radio emission created by neutrino interactions. To date four science flights have been completed, with a fifth flight proposed for the near future. In this talk I give an overview of ANITA with a focus on the third and fourth flights and discuss the recently completed analyses of ANITA-3 data. The most sensitive neutrino search from ANITA-3 found a single neutrino candidate event on an expected background of 0.7 (+0.8 -0.3) events. The analysis set the best limit on the diffuse flux of ultra-high energy neutrinos at energies above 10^19.5 eV. Although consistent with the initial background estimate, interpretation of the surviving event as a neutrino is still plausible after additional post-unblinding scrutiny. The ANITA-3 analyses also found nearly 30 extensive air shower events in an alternative polarization to the neutrino search. All but one of these events are identified as ultra-high energy cosmic rays. We give a speculative interpretation of the remaining alternative polarization event.

Speaker: Ben Strutt (UCLA)

Slides ANITA_TeVPA2018.pdf

196 GRAND: The Giant Radio Array for Neutrino Detection

Progress in finding the origin of ultra-high-energy cosmic rays (UHECRs) will come from discovering the secondary UHE neutrinos produced in UHECR interactions. Yet, the flux of UHE neutrinos may lie beyond the reach of existing detectors and their possible upgrades. GRAND is a planned large-scale UHE observatory designed to discover UHE neutrinos even if their flux is low. It will do so by measuring the radio emission from extensive air showers triggered by UHE particles in the atmosphere --- not only neutrinos, but also cosmic rays and gamma rays. For UHE neutrinos, GRAND aims to reach a sensitivity of ∼10−10 GeV cm−2 s−1 sr−1 in 3 years, a factor-of-100 improvement over potential upgrades of existing detectors. Further, GRAND aims for an aperture to cosmic rays above 1010 GeV that is 20 times larger than in Auger, and a sensitivity to a flux of UHE gamma rays that is 10 times better. Besides, GRAND will be a powerful instrument for radioastronomy. In this talk, I will showcase the rich science program of GRAND, its design, and its construction status and plans.

Speaker: Mauricio Bustamante (Niels Bohr Institute)

Slides 2018-08-28-Bustamante-TeVPA.pdf

197 Radar detection of the PeV-EeV cosmic neutrino flux

At the highest energies the cosmic neutrino flux drops rapidly and an even larger detection volume than the cubic kilometer of ice currently probed by the IceCube experiment is needed. Due to its long attenuation length, the radio signal provides the ideal means to cover such large volumes. Nevertheless, the direct radio emission from a neutrino induced particle cascade becomes detectable around EeV energies. This leaves a sensitivity gap in the PeV-EeV range. To cover this sensitivity gap, we discuss the radar detection technique as a method to probe the PeV-EeV cosmic neutrino flux. To investigate the feasibility of the radar detection method, in May 2018 a beam test experiment was performed at the Stanford Linear Accelerator Center (SLAC). We present first results of this experiment and discuss the potential of the radar detection technique in detail.

Speaker: Dr Krijn de Vries (VUB/IIHE)

Slides TeVPA_v2.pdf

198 VHE neutrinos and gamma-rays from dense clusters surrounding GRBs

Massive stars with strong stellar winds are expected to be progenitors of the long gamma-ray burtsts (GRBs). The winds of these stars are expected to form a wind cavities within the dense clusters. We consider a scenario in which protons, accelerated within the jet of GRB, escape from the GRB jet to the wind cavity. They are transported with the massive star wind to the dense open cluster where they interact with the matter producing high energy gamma-rays and neutrinos. It is argued that VHE neutrino (and possibly also gamma-ray) afterglows can be produced around observed GRBs for a long time after GRB explosion. Therefore, such emission might be detected in the stacked analysis of the VHE neutrino events (IceCube and Antares data) and possibly also VHE gamma-ray emission (e.g. in the HAWC data) around known GRBs.

Speaker: Prof. Wlodek Bednarek (University of Lodz)

Slides wb-neu-grb-talk.pdf

199 Results of IceCube searches for neutrinos from blazars using eight years of through-going muon data from the Northern Hemisphere

Located at the South Pole, the IceCube Neutrino Observatory is the world largest neutrino telescope, instrumenting one cubic kilometre of Antarctic ice at a depth between 1450m to 2450m. In 2013 IceCube reported the first observations of a diffuse astrophysical high-energy neutrino flux. Although the IceCube Collaboration has identified more than 100 high energy neutrino events, the origin of this neutrino flux is still not known. Blazars, a subclass of Active Galactic Nuclei and one of the most powerful classes of objects in the universe, have long been considered promising sources of high energy neutrinos. A blazar origin of this high-energy neutrino flux can be examined using stacking methods testing the correlation between IceCube neutrinos and catalogs of hypothesized sources. Here the IceCube results for 1301 blazars from the third catalog of hard Fermi-LAT sources (3FHL) will be presented. The analysis is performed on 8 years of through-going muon data from the Northern Hemisphere, recorded by IceCube between 2009 and 2016.

Speaker: Matthias Huber (TU Munich)

Slides BerlinTeVPA2018.pdf

Wednesday, 29 August

Gamma Rays

Chair: Rolf Buehler

200 Gamma-ray astronomy: Status and perspectives

Follows soon.

Speaker: Prof. Werner Hofmann (Max-Planck-Institut für Kernphysik)

Slides 2018_08_TeVPA_Hofmann.pdf

201 Morphology study of a radio galaxie

The current generation of Imaging Atmospheric Cherenkov Telescopes has its resolution power limited to few arcminute scale. Recently, new simulations and analysis techniques, applied to H.E.S.S. observations, made possible the measure of the extension of very high energy (VHE; E > 100 GeV) gamma-ray sources below one arcminute. The improved understanding of the point spread function (PSF) of H.E.S.S. allows to investigate the morphology of nearby extragalactic sources such as radio-galaxies. The results of such sophisticated techniques, applied to the prominent radio galaxy Centaurus A, will be presented at the conference.

Speaker: Dr David Sanchez (CNRS/LAPP)

Slides CenA_Morpho_Sanchez.pdf

202 HAWC Observations on Two Nearby Pulsar Wind Nebulae Constrain the Origin of Local Positrons

Nearby electron and positron accelerators, especially Pulsar Wind Nebulae, have been proposed as potential origins of the local multi-GeV positron excess. The HAWC Gamma-Ray Observatory has reported very extended TeV gamma-ray emission around two nearby middle-aged pulsars Geminga and B0656+14, suggesting ultra-relativistic electrons and positrons accelerated in our backyard. The gamma-ray profiles up to tens of parsecs around these two pulsars provide a direct constraint on the diffusion of electrons and positrons in the interstellar medium. We will present the spatial and spectral studies on these two TeV gamma-ray sources and the derived positron contribution at Earth.

Speaker: Dr Hao Zhou (Los Alamos National Laboratory)

Slides 20180829.pdf

203 Propagation of TeV gamma rays in intergalactic space

Follows soon.

Speaker: Avery Broderick (Waterloo Uni., Perimeter Inst)

Slides talk.pptx

10:30 Coffee Break

Dark Matter

Chair: Elisa Püschel

204 Direct Dark Matter detection

Follows soon.

Speaker: Teresa Marrodan (MPIK Heidelberg)

Slides Marrodan_TeVPA_2018Berlin.pdf

205 Indirect DM searches

Follows soon.

Speaker: Francesca Calore (CNRS, LAPTh)

Slides TeVPA2018_Calore.pdf

206 Dark Matter in the Milky Way. Distribution, uncertainties, and their impact on the search for new physics

The distribution of Dark Matter in galaxies is one remarkable output of structure formation in a cosmological context, and an important input for the searches of the nature of Dark Matter. In this talk I will present the results of recent, fully data-driven analysis of the determination of the Dark Matter content in the Milky Way. I will also show how the uncertainties obtained with this observation-driven approach affect the interpretation of direct and indirect searches, and eventually the searches for the very nature of the Dark Matter.

Speakers: Dr Fabio Iocco (ICTP-SAIFR), Dr Fabio Iocco (ICTP-SAIFR)

Slides

• iocco-1.pdf
• iocco-2.pdf
• iocco-3.pdf

207 Voyager probing Dark Matter

We take advantage of spacecraft Voyager 1's capacity for detecting interstellar CRs since it crossed the heliopause in 2012. This opens up a new avenue to probe DM through CR electrons and positrons in the sub-GeV energy range. From a complete description of the transport of electrons and positrons at low energy, we derive predictions for both the secondary astrophysical background and the pair production mechanisms relevant to DM annihilation or decay down to the MeV mass range. We combine the constraints from the Voyager and AMS-02 data to get novel limits covering a very extended DM particle mass range, from MeV to TeV. For p-wave annihilation, we make use of the Eddington method to compute the velocity average annihilation cross section from the most recent constrained mass model of the Galaxy. Primordial black holes are also motivated candidates for dark matter. Black holes with a mass smaller than ~10^17 g are expected to inject electrons and positrons in the Galaxy through Hawking radiation. We derive novel constraints on the contribution of primordial black holes to dark matter in this mass window. Though extracted from a completely different and new probe, these bounds have a strength similar to those obtained with the extragalactic gamma ray background.

Speaker: Mr Mathieu Boudaud (LPTHE, Paris, France)

Slides TeVPA_2018.pdf

12:30 Lunch Break

Galactic Science: 2

Chair: Jacco Vink

Conveners: Mr Dmitry Khangulyan (Rikkyo University), Emma de Ona Wilhelmi (CSIC-IEEC), Dr Luigi Tibaldo (IRAP)

208 The supernova driven interstellar medium on local and global scales

During the last two decades due to the increase of computing power and software developments, such as adaptive mesh refinement, substantial progress has been made in numerical modeling of the interstellar medium (ISM). It has been found that the bulk of kinetic and thermal energy input stems from supernovae and to a lesser extent from stellar winds. Our group has shown that on mesoscales (1 kpc x 1 kpc x 15 kpc in the disk and perpendicular to it, respectively) subparsec scale resolution can be achieved, so that major physical processes can be described correctly, although the end of the turbulent cascade is still out of range. An important result is that radiative cooling and the ionisation structure of the plasma are non-linearly coupled so that the often used assumption of collisional ionisation equilibrium in a dynamical plasma might give erroneous results, both in temperature derivation from spectral lines and in the dynamics of the plasma itself. On a local scale, we show that it is possible to derive supernova explosion sites and times near Earth from modeling the fluence of the radioisotope 60Fe, generated in explosive nucleosynthesis and found in the ferromanganese crust and sediments on deep sea ocean floors.

Speaker: Dieter Breitschwerdt (Technische Universität Berlin)

Slides ISM_Halos_TeVPA_DB_0117.pdf

209 Galaxy formation with cosmic rays: the importance of the gamma-ray window

Star formation in galaxies appears to be self-regulated by energetic feedback processes. Among the most promising agents of feedback are cosmic rays (CRs), the relativistic ion population of interstellar and intergalactic plasmas. In these environments, energetic CRs are virtually collisionless and interact via collective phenomena mediated by kinetic-scale plasma waves and large-scale magnetic fields. The enormous separation of kinetic and global astrophysical scales requires a hydrodynamic description. We develop a new macroscopic theory for CR transport in the self-confinement picture, which includes CR diffusion and streaming simultaneously. The interaction between CRs and electromagnetic fields of Alfvénic turbulence provides the main source of CR scattering. We account for energy exchange of CRs and Alfvén waves via the gyroresonant instability and include other wave damping mechanisms. These theoretical advances enable us to simulate CR physics with the three-dimensional magneto-hydrodynamical simulation code AREPO, which employs an innovative moving mesh geometry. I will demonstrate that CRs play a decisive role on all scales relevant for galaxy formation, from individual supernova remnants, to the multiphase medium in our Galaxy up to scales relevant for galaxy formation. In particular, I will show how TeV shell-type supernova remnants can be used to infer the in-situ coherence scale of Galactic magnetic fields. Finally, I will discuss the non-thermal gamma-ray emission of Milky-Way like galaxies and how the next-generation instruments such the Cherenkov Telescope Array (CTA) can be used to infer properties relevant for galaxy formation.

Speaker: Prof. Christoph Pfrommer (AIP)

Slides Pfrommer_TeVPA18.pdf

210 The gamma-ray emission properties of translucent cirrus clouds

Using archival data from the Fermi Large Area Telescope in the 0.1 - 300$\,$GeV photon energy range, we detect and characterise the gamma-ray emission counterpart on parsec scales to the optically translucent, infrared-emitting and dominantly neutral "Cirrus" clouds, which carry the bulk of gas mass in the disk of the Milky Way at the solar circle. The detection is achieved using a stacking analysis of a statistical sample of clouds at high galactic latitude, selected according to dust column as derived from the Planck all-sky maps of dust opacity in the 353 micron band. We analyse substacks of clouds ordered according to gas column, as unambiguously derived from a cross-calibration between the dust emission at 353 micron and the emission in the optically thin 21$\,$cm hyperfine hydrogen line. Both the amplitude and form of the 1 - 100$\,$GeV emission SED of Cirrus are consistent with the predicted emission from the decay of pions produced from collisions between gas nuclei and CR protons with a flux similar to that measured at the Earth. This is jointly consistent with there being no systematic contrast between the CR proton fluxes incident on the cirrus clouds and the fluxes within the clouds, and, further, with there being no systematic variation of the CR proton flux with vertical position in the gas layer at the solar circle. We also place limits on the putative inverse-Compton component of gamma-ray emission resulting from the scattering of infrared photons from dust grains in the clouds by CR electrons.

Speaker: Dr Richard Tuffs (Max-Planck-Institut fuer Kernphysik)

Slides rtuffs_tevpa.ppt

211 Investigating Particle Acceleration in Star Forming Regions in the Cygnus Constellation with HAWC

Massive Star clusters and Super bubbles in star forming regions (SFRs) have been postulated as possible sources of cosmic rays in our galaxy. At the interaction sites of stellar winds of O type stars, charged particles can be accelerated to TeV energies. One possible example of this is a Fermi-LAT cocoon, an extended region of gamma-ray emission detected by Fermi-LAT and attributed to a cocoon of freshly accelerated cosmic rays (CRs) in the SFR region of Cygnus X near OB2 association. So far, the cocoon has been only detected at GeV energies. The HAWC observatory has detected a TeV gamma-ray source 2HWC J2031+415 co-located with the cocoon. Spectral and Morphological studies of the region with HAWC and Fermi-LAT data reveal the HAWC source as a likely counterpart of the cocoon. The cocoon spectrum extends from GeV to TeV range. Using HAWC data, we are the first to measure a cut off in the TeV emission associated with an SFR.

Speaker: Binita Hona (Michigan Technological University)

Slides tevpa_hona.pdf

212 Nonthermal hard X-ray and TeV gamma-ray diagnostics of diffusion coefficient near supernova remnants shocks

The shock waves at supernova remnants (SNRs) are the prominent acceleration sites of Galactic cosmic rays. The diffusion of the accelerated particles around the SNR shock is assumed to be Bohm type, where the diffusion coefficient is proportional to the particle energy. The details, however, remain unrevealed. There is a method to diagnose the diffusion coefficient from the cutoff shape of the electron distribution, corresponding to the synchrotron X-ray spectrum. We apply this to nonthermal hard X-ray observations of four synchrotron-dominated Galactic SNRs: RX J1713.7$-$3946, Vela Jr., G1.9$+$0.3, and SN 1006. Recent NuSTAR observations provide us with the spatially-resolved hard X-ray spectra up to tens of keV. The precise measurement of synchrotron X-ray cutoff form constrains the diffusion coefficient around the cutoff energy of electron. Irrespective of the diffusion type, i.e. the energy dependence on the coefficient, the diffusion coefficient around the maximum energy of electron is obtained to be roughly comparable. For example, it is about 10$^{25}$ cm$^2$/s in 20-40 TeV with magnetic field of 100 $\mu$G for RX J1713.7$-$3946 NW. We also test the application to the gamma-ray cutoff form using TeV gamma-ray observations with H.E.S.S. We report and discuss its result.

Speaker: Naomi Tsuji (Rikkyo University)

Slides 20180829_TeVPA2018.key.pdf

213 The Monster Next Door Fermi-LAT observations of supernova remnant N132D in the Large Magellanic Cloud

Supernova remnant (SNR) N132D, located in the Large Magellanic Cloud, represents a unique opportunity for the study of gamma-ray emission from shock-accelerated cosmic rays (CRs) in another galaxy since it stands as the first and only extra-galactic SNR detected in gamma-rays. N132D is one of the brightest SNRs in the local Universe in the X-ray, infrared and radio bands, and it has also been detected in TeV energy gamma-rays. N132D's apparent interaction with a giant molecular cloud strongly favors the scenario where the gamma-ray emission results from CR hadrons interacting with dense ambient media. We report on the detection of N132D with the Fermi-LAT and characterize the emission in the MeV-GeV band. Additionally, we establish an upper-limit on the non-thermal contribution to the X-ray spectrum obtained using Chandra observations. Our results allow us build a very complete picture of the properties of the system and its progenitor, ultimately helping us better understand CR acceleration in SNRs.

Speaker: Dr Daniel Castro (Harvard-Smithsonian Center for Astrophysics)

Slides dc-presentation-v1.pdf

Gamma Rays: 4

Chair 1: Stefan Ohm | Chair 2: Ruben Lopez-Coto | Chair 3: Sara Buson | Chair 4: Felicia Krauss | Chair 5: Francesco Longo | Chair 6: David Sanchez | Chair 7: Konstancja Satalecka

Conveners: Dr Ruben Lopez-Coto (INFN Padova), Dr Sara Buson (NASA-GSFC), Mr Stefan Ohm (DESY, Zeuthen)

214 The First Catalog of Fermi-LAT sources below 100 MeV

Previous analyses of point sources in the gamma-ray range were done only below 30 MeV (COMPTEL) or above 100 MeV (Fermi-Large Area Telescope). Below 30 MeV, the imaging Compton telescope (COMPTEL) detected 26 steady sources in the energy range from 0.75 to 30 MeV. At high energy, the LAT detects more than three thousand sources between 100 MeV and 300 GeV (3FGL). Since the Fermi-LAT detects gamma rays down to 20 MeV, we create a list of sources detected in the energy range between 30 MeV and 100 MeV, using PGWave, a background independent tool that makes use of a wavelet-based method. This closes a gap of point source analysis between the COMPTEL catalog and the Fermi-LAT catalog. We present the Fermi-LAT low energy catalog (1FLE) of sources detected in the 30 MeV - 100 MeV range, based on 8 years and 9 months of Fermi-LAT data.

Speaker: Mr Giacomo Principe (ECAP - Erlangen Nurenberg University)

Slides 1FLE_Principe_TeVPA2018.pdf

215 The gamma rays origin of Fermi-LAT blazars, beyond the broad line region?

The gamma-ray emission in broad-line blazars is generally explained as inverse Compton (IC) radiation of relativistic electrons in the jet scattering optical-UV photons from the broad-line region (BLR), the so-called BLR external Compton (EC) scenario. We test this scenario on the Fermi gamma-ray spectra of 106 broad-line blazars detected with the highest significance or largest BLR, by looking for cut-off signatures at high energies compatible with γ-γ interactions with BLR photons. We do not find evidence for the expected BLR absorption. For 2/3 of the sources, we can exclude any significant absorption (τmax < 1), while for the remaining 1/3 the possible absorption is constrained to be 1.5-2 orders of magnitude lower than expected. This result holds also dividing the spectra in high- and low-flux states, and for powerful blazars with large BLR. Only 1 object out of 10 seems compatible with substantial attenuation (τmax > 5). We conclude that for 9 out of 10 objects, the jet does not interact with BLR photons. Gamma-rays seem either produced outside the BLR most of the time, or the BLR is ˜100 × larger than given by reverberation mapping. This means that EC on BLR photons is disfavoured as the main gamma-ray mechanism, versus IC on IR photons from the torus and without absorbtion by the BLR, broad-line blazars can become copious emitters above 100 GeV, as demonstrated by 3C 454.3, in this scenario, we will expect to observe this type of sources with the future IATCs instruments as CTA.

Speaker: Dr Sara Cutini (INFN Perugia)

Slides TeVPA_Cutini.pdf

216 Unravelling the complex behaviour of our closest very-high-energy gamma-ray blazars, Mrk421 and Mrk501

Because of their brightness and proximity (z=0.03), Mrk421 and Mrk501 are among the very-high-energy gamma-ray objects that can be studied with the greatest level of detail. This makes them excellent astrophysical high-energy physics laboratories to study the nature of blazars. Since 2009, there has been an unprecedentedly long and dense monitoring of the radio to very-high-energy gamma-ray emission from these two archetypical TeV blazars. In the conference I will report recent highlight results obtained from these multiwavelength campaigns. Despite some differences in the variability patterns of these two sources, there are also a number of similarities that support a broadband emission dominated by leptonic scenarios, as well as indications for in situ electron acceleration in multiple compact regions. I will discuss the complexity in the temporal evolution of their broadband emission and the presence of different flavors of flaring activity. I will also show detailed observational and theoretical results related to the 2-week long highest X-ray activity observed with Swift-XRT since its launch almost 14 years ago. These multi-instrument observations have yielded thought-provoking results, and demonstrate the importance of performing a continuous monitoring over multi-year timescales to fully characterise the dynamics of blazars.

Speaker: David Paneque (Max Planck Institute for Physics)

Slides Paneque_TeVPA2018.pdf

217 MAGIC observations of VHE gamma rays from the flaring blazar TXS 0506+056 coincident with high-energy neutrino IceCube-170922A and implications

On 22$^{\text{nd}}$ September 2017, a high energy neutrino was detected by the IceCube observatory in spatial coincidence with the blazar TXS 0506+056, which was observed to be flaring in the GeV band by the Fermi-LAT telescope. This coincidence triggered a series of multi-wavelength observations by several telescopes on ground and in space. On 24$^{\text{th}}$ September 2017, the MAGIC telescopes started follow-up observations of this source and shortly afterwards reported the detection of VHE gamma rays from its sky position. Here we describe the observational results obtained with the MAGIC telescopes and multi-wavelength data collected during the flaring event. These results constitute the first detection of VHE gamma rays from a potential astrophysical source of high-energy neutrinos, and offer important new constraints on the mechanisms of particle acceleration and radiation in blazars. They may also provide fresh insight into high-energy cosmic ray acceleration in AGN jets.

Speaker: Luca Foffano (University of Padova, INFN)

Slides MAGIC-TeVPA18-Berlin.pdf

218 Is PKS 0625-354 a radio galaxy?

The catalogue of TeV gamma-ray emitting objects includes about 80 extragalactic sources, among which most are blazars. Only a few of them belong to the class of radio galaxies or misaligned blazars. The latter includes PKS 0625-354, an object that was detected in very high energy gamma rays within only 5.5 hours of H.E.S.S. observations. Along with the H.E.S.S. observations, PKS 0625-354 was also observed with other instruments, in different frequencies, including: Fermi-LAT, Swift-XRT, Swift-UVOT and ATOM. H.E.S.S. data together with the multiwavelength (MWL) ones shade more light on current classification of PKS 0625-354 as a radio galaxy. Variability patterns observed in PKS 0625-354, together with the broadband spectral energy distribution (SED) modelling have shown that blazar-like scenario for this source is very plausible. In this talk I will report result of the H.E.S.S. and MWL observations of PKS 0625-354. I will also discuss possible interpretation of the broadband SED of PKS 0625-354 and features that classify the object as a blazar.

Speaker: Dr Alicja Wierzcholska (Institute of Nuclear Physics PAS)

Slides pks0625_TeVPa_AWierzcholska_v3.pdf

219 Very high energy gamma rays from Centaurus A and two zone lepto-hadronic modelling

The spectrum of UHECR signal events above 55 EeV from Centaurus A (Cen A) can provide a useful hint about the injected spectrum of cosmic ray nuclei. The injected spectrum connects UHECRs to the HESS detected GeV-TeV gamma rays. The 8 years of Fermi-LAT data from Cen A has significant hardening in the GeV energy. In an attempt to understand the origin of this hardening, we explore two emitting zones in the jet of Cen A. We consider two scenarios: (i) Two zone synchrotron self-Compton (SSC) and external-Compton (EC) models, (ii) Two zone SSC, EC and photo-hadronic emission from cosmic ray interactions. The GeV hardness observed by Fermi-LAT can be explained using these two scenarios, where zone 2 EC emission is very important. Photo-hadronic emission in scenario (ii) can explain VHE data with the same spectral slope as obtained through fitting UHECRs from Cen A.

Speaker: Dr Jagdish Joshi (University of Johannesburg)

Slides Lepto_HadronicTeVPA_Joshi.pdf

220 The electrostatic instability for realistic pair distributions in blazar/EBL cascades

Very high-energy gamma-rays from TeV blazars interact with the extragalactic background light producing pair beams. These pairs emit secondary photons in the GeV range by the inverse Compton scattering. However, the measured GeV signal is smaller compared to one predicted from the full electromagnetic cascade. From what follows that the pairs are affected by some other physical processes leading to the reduction of their energy flux. One relevant mechanism is the electrostatic instability induced by the pair beams in the IGM plasma. We revisited the linear growth rate of this instability analytically for the realistic distribution function of pairs without inverse Compton cooling. Our results indicate that the finite angular spread of the beam has a considerable effect on the electrostatic growth rate. Moreover, the growth rate is much higher than in the case when the inverse Compton scattering is included. To explore the non-linear beam evolution, we made Particle-In-Cell simulations. The simulated beam loses 1% of its energy during the simulation, while the energy lose would achieve 100% after 100 simulation times. Using analytical estimations, we extrapolated our results to the realistic pair beam parameters and found the lower limit on the relaxation time of the beam. The pair beam can dissipate its energy faster than the inverse Compton scattering, but a more accurate model is required to make firm predictions for individual blazars.

Speaker: Dr Sergei Vafin (Institute for Physics and Astronomy, University of Potsdam, D-14476 Potsdam, Germany)

Slides TEVPA_2018_Vafin.pdf

Neutrino Astronomy: 4

Chair 1: Fabrizio Tavecchio | Chair 2: Andrea Palladino | Chair 3: Francesco Villante | Chair 4: Joshua Wood | Chair 5: Summer Blot | Chair 6: Markus Ahlers

Conveners: Dr Aart Heijboer (NIKHEF), Dr Andrea Palladino (DESY), Claudio Kopper (University of Alberta)

221 KM3NeT: a multi-site neutrino telescope in the Mediterranean Sea to address key questions in Astro-Particle and Particle Physics

Recently it has been reported by the IceCube detector, which is installed under the thick Antarctic ice, evidence of the existence of a high-energy flow of cosmic neutrinos. Today, the scientific community requires that a neutrinos telescope located in the northern hemisphere verify and complete the results of IceCube, so as to allow observation of high-energy neutrinos across the sky. The Mediterranean Sea is the ideal place for this new structure. Furthermore, one of the open issue in the particle physics field is the determination of the neutrino mass hierarchy. KM3NeT, a network of neutrino telescopes in the Mediterranean Sea, is the following step for the next-generation neutrino telescopes. Its first phase is under construction by the collaboration, on two sites. The first one, KM3NeT-It, near Sicily, will focus on high energy neutrinos astronomy (ARCA). The second one, KM3NeT-Fr, near Toulon in France, will focus on the studies of oscillations with atmospheric neutrinos (ORCA) with the main objective of determining the neutrinos mass hierarchy. They consist in a regular 3D array of DOMs (Digital Optical Modules) equally spaced along flexible lines anchored on the seabed. First, a detailed overview of the detectors and planned results will be given. Then, a report on the phase one construction will be made. Finally, details on calibration techniques will be presented, with an emphasis on time calibration, water properties and positioning measurements.

Speaker: Pasquale Migliozzi (INFN Napoli)

Slides TeVPA2018Migliozzi.pptx

222 The Neutrino-BL LAC Connection

Despite intense inquiry, the sources at the origin of the high-energy neutrinos revealed by IceCube are still unknown. The potential correlation of an IceCube event with a flaring gamma-ray source has recently focused the attention on BL Lac objects, active galactic nuclei with a relativistic jet pointing to the Earth. Since the nuclei of these sources lack bright thermal components, it is generally expected that, for acceptable values of the high-energy proton luminosity, the neutrino output (mediated by photopion reactions with photons produced within the jet) is low. I will discuss how this problem can be overcome considering alternative sources of soft photons external to the jet, as a slow sheath surrounding the jet or the (likely radiatively ineffcient) accretion ow.

Speaker: Fabrizio Tavecchio (Brera Observatory)

Slides TavecchioTeVPA.pdf

223 Limits on the flux of tau neutrinos from 1 PeV to 3 EeV with the MAGIC telescopes

A search for tau neutrino induced showers with the MAGIC telescopes is presented. The MAGIC telescopes located at an altitude of 2200 m a.s.l. in the Canary Island of La Palma, can point towards the horizon or a few degrees below, across an azimuthal range of about 80 degrees. This allows to search for a signature of particle showers induced by earth-skimming cosmic tau neutrinos in the PeV to EeV energy range arising from the ocean. In this talk we show how such air showers can be discriminated by MAGIC from the background of very inclined hadronic showers by using Monte Carlo simulations. The analysis of about 30 hours of data taken towards the sea leads to a 90\% C.L. point source limit for tau neutrinos in the energy range from $1.0 \times 10^{15}$ eV to $3.0 \times 10^{18}$ eV of about $E_{\nu_{\tau}}^{2}\times \phi (E_{\nu_{\tau}}) < 2.0 \times 10^{-4}$ GeV cm$^{-2}$ s$^{-1}$, for an assumed power-law neutrino spectrum with spectral index $\gamma$=-2. However, with 300 hours and in case of an optimistic neutrino flare model, limits of the level down to $E_{\nu_{\tau}}^{2}\times \phi (E_{\nu_{\tau}}) < 8.4 \times 10^{-6}$ GeV cm$^{-2}$ s$^{-1}$ can be expected. This is first time that such limit has been calculated with realistic assumptions and using background data collected by MAGIC, which gives a realistic illustration of the potential of the Cherenkov technique for this topic of research.

Speaker: Dariusz Gora (IFJ PAN, PL-31342 Krakow, Poland, DESY Germany)

Slides MAGIC_DG_TeVPA_2018.pdf

224 Searching for Optical Counterparts to High-Energy Neutrino Sources with the Zwicky Transient Facility

The IceCube neutrino observatory has detected a flux of extragalactic neutrinos. However, the origin of the neutrinos is still unknown. Among the possible candidates are Gamma-Ray Bursts (GRBs), Core-Collapse Supernovae (SNe), Active Galactic Nuclei (AGN) and Tidal Disruption Events (TDEs) - all are accompanied by a characteristic optical counterpart. Therefore, the goal is to identify the neutrino sources by detecting their optical counterpart with the Zwicky Transient Facility (ZTF). ZTF features a high cadence all-sky survey enabling a real time correlation of optical transients with high energy neutrino candidates. A summary of the planned neutrino science program with ZTF will be presented.

Speaker: Dr Ludwig Rauch (DESY)

Slides tevpa_rauch.pdf

225 Black hole interference patterns in flavour oscillations

Motivated by neutrino astronomy, we consider a plane wave of coupled and massive flavours, scattered by a static black hole, and describe analytically and numerically the corresponding oscillation probability in the surrounding space. Both the interpretation as particles travelling along geodesics and as scattered waves are studied, and consistently show a non-trivial and potentially long range interference pattern.

Speaker: Dr Jean Alexandre (King's College London)

Slides NRNeutrinoOscillations.pdf

226 Bounds on ultra-long-range flavored neutrino interactions with IceCube

High-energy astrophysical neutrinos, with TeV--PeV energies, are acutely sensitive to the existence of potential new flavor-dependent interactions with the electrons around them. For the first time, we probe this possibility by looking for deviations in the flavor composition of the astrophysical neutrinos seen by IceCube. At these energies, the relative contribution of standard oscillations is weakened, compared to the contribution of the new interaction . We choose a physically motivated scenario where the interaction is mediated by a new neutral vector boson. We explore the possibility that it is ultra-light, with a mass of $10^{-10}$ eV or smaller, which makes the interaction range ultra-large, between $10^4$ km and a few Gpc. Because the number of electrons contained within these distances is huge, they could signifcantly distort the flavor composition of astrophysical neutrinos, even if the new coupling is feeble. Based on IceCube results on flavor composition, we set tight bounds on the existence of ultra-light mediators, down to tiny masses of $10^{-35}$ eV.

Speaker: Dr Mauricio Bustamante (Niels Bohr Institute)

Slides 2018-08-29-Bustamante-TeVPA.pdf

Particle Physics: 1

Chair 1: Anatoli Fedynitch | Chair 2: Florencia Canelli

Conveners: Dr Anatoli Fedynitch (DESY), Prof. Florencia Canelli (University of Zurich), Pedro Machado (FNAL)

227 Recent progress concerning Atmospheric Charm

I will discuss the production of charm due to CR interactions in the atmosphere and the implications for astrophysical experiments. I will review both recent theoretical progress in QCD computations of prompt neutrino fluxes and recent developments and attempts of incorporating charm in hadronic interaction models traditionally used for studies of extended air showers.

Speaker: Dr Maria Vittoria Garzelli (University of Delaware)

Slides semberli.pdf

228 Probing hadronic interactions at ultra high energies with extensive air showers

Due to the discrepancy between the observed and predicted average number of muons in air showers, the connection between the average muon content and the development of air showers has been studied extensively in the past. Here we present a study of the physics of the fluctuations of the muon content. In addition to proving that the fluctuations must be dominated by the first interactions, we show that the fluctuations and entire shape of the distribution of the number of muons is determined by the energy spectrum of hadrons in the first interaction.

Speaker: Felix Riehn (lip)

Slides tevpa2018_180829_riehn.pdf

229 A ranking of production cross-sections for light cosmic rays : LI, BE, B, C, AND N

The precision of the new generation of cosmic-ray (CR) experiments, such as AMS-02, PAMELA, CALET, and ISS-CREAM, is now reaching the percent level in a wide energy range from GeV/n (per nucleon) to multi-TeV/n. A precise understanding of cosmic-rays production and propagation as well as stringent constraints on dark matter are guaranty results from a precise interpretation of the measured fluxes. Meanwhile, a major obstacle in doing so is the current uncertainty in the isotopic production cross sections which is often as high as 20-50% or even larger in some channels. This embarrassing situation is gaining momentum in the astrophysics community which call for a dedicated experimental effort. I will first illustrate the impact of the current cross-section models on the interpretation of the data. Measuring the all set of cross-sections needed is of course a huge work that requires an incremental approach. In a recent work my collaborators and I aim at providing the community with the ranking of the cross sections contributing to the production of the most astrophysically important isotopes of Li, Be, B, C, and N. I will present this ranking and give an evaluation of the beam time necessary to reach a 3% precision in the production cross-sections pertinent to the AMS-02 experiment. This first roadmap may become a starting point in the planning of new measurement campaigns that could be carried out in several nuclear and/or particle physics facilities around the world.

Speaker: Mr Yoann GÉNOLINI (ULB)

Slides TeVPa_Genolini.pdf

230 Accelerator-based light particle searches form NA62

Follows soon.

Speaker: Fabio AMBROSINO (Università e Sezione INFN Napoli)

Slides Ambrosino-TevPA2018.pdf

231 Low-scale leptogenesis with 3 right-handed neutrinos

We provide the first systematic study of the low-scale leptogenesis scenario in the minimal Standard Model extended with 3 right-handed neutrinos having masses at the GeV scale. We highlight and discuss the differences between the 2- and the 3-right-handed neutrino cases, the major qualitative distinction being the possibility, in the latter scenario, of probing part of the parameter space at the LHC. Moreover, 3-right-handed neutrinos allow for the generation of a CP-asymmetry already in the oscillating sterile sector, without the need of relying on flavour asymmetric washout. We quantitatively study the differences between the parameter space of solutions in the two scenarios, highlighting the viability of the models and their testability in current and future experiments, as well as the different impact of the identified solutions in neutrino observables, as for instance in the neutrinoless double beta decay expected rate.

Speaker: Dr Michele Lucente (CP3 - UCLouvain)

Slides TeVPA2018_Lucente.pdf

232 Interesting Models unifying Neutrino Mass, Dark Matter, Origin of PMNS and CKM, and GUT

The Standard Model of particle physics have been extremely successful so far, but there are still many unanswered questions like the origin of neutrino mass, nature of dark matter, the source of quark and lepton flavor mixing and their possible correlation, the theory of grand unification of all SM interactions. In this talk I will focus on some interesting models that attempt to answer these questions and possible correlation between them. Embedding a Pati-Salam quark-lepton unification symmetry, SU(4)$_c\otimes$SU(2)$_L \otimes$U(1)$_R$, into SU(7) GUT with a Scotogenic radiate neutrino mass and LHC phenomenology will be discussed. I will also touch on $G_{SM}\otimes$U(1)$_{B-L}$ with residual $Z_4$ symmetry leading to Scotogenic radiative Dirac neutrino masses with dark matter, 0$\nu$4$\beta$ and absence of $0\nu$2$\beta$ signal and phenomenology of related rare processes. Possible common origin of CKM and PMNS mixings in a complete model. Other possible topics will include chiral dark sector with composite dark matter leading to Scotogenic two loop neutrino mass and neutrino portal to SM.

Speaker: Oleg Popov (Seoul Netional University of Technology and Science)

Slides SU7_Scoto_SU4SU2U1_opopo001_TeVPA2018.pdf

233 Constraining generalised neutrino interactions with COHERENT data

Coherent neutrino-nucleus scattering can provide stringent constraints on generalised effective neutrino-quark interactions. While neutrino-quark non-standard interactions (NSI) represent a subset of these generalised interactions, in full generality they may include all possible four-fermion Lorentz structures. Depending on their strength, these new interactions can sizably modify the coherent neutrino-nucleus elastic scattering process and thus they can be constrained by the recent COHERENT data. We derive constraints on these generalised interactions by considering scalar, vector and tensor couplings.

Speaker: Valentina De Romeri (IFIC (CSIC-Univ. Valencia))

Slides De_Romeri_TeVPa.pdf

15:45 Coffee Break

Cosmic Rays: 4

Chair 1: Don Ellison | Chair 2: Denise Boncioli | Chair 3: Andrew Taylor | Chair 4: Daniele Gaggero |
Chair 5: Tony Bell | Chair 6: Markus Ahlers

Conveners: Andrei Bykov (Ioffe Physico-Technical Institute), Dr Sabrina Casanova (IFJ PAN &amp; MPIK HD), Dr denise boncioli (DESY)

234 Building the Galactic magnetic halo

The Cosmic Ray (CR) physics has entered a new era driven by high precision measurements coming from direct detection (especially AMS-02 and PAMELA) as well as gamma-ray observations (Fermi-LAT) which requires the development of more refined models for the CR acceleration and propagation. In this talk I will present a model for the generation of the Galactic magnetic halo where Cosmic Rays propagate. The magnetic halo is builded by two separated processes: 1) the large-scale magnetic turbulence generated into the galactic plane and advected away from it while cascading towards smaller scales and 2) the small-scale turbulence self-generated by CRs that escape from the Galaxy. The decay process of large scale turbulence naturally predicts a magnetic halo size of ~ 2-5 kpc, as required by the majority of CR models. Moreover, the interplay between these two processes can explain the break observed in the CR spectrum at ~300 GV by AMS-02.

Speaker: Dr Giovanni Morlino (Gran Sasso Science Institute)

Slides Morlino_TeVPA-2018.pdf

235 Time-dependent CR feedback on shocks

Non-linear diffusive shock acceleration (NDSA) is believed to be the mechanism responsible for the acceleration of cosmic-rays in supernova remnants. But current steady-state models fail to reproduce spectral features observed in supernova remnants, like spectral breaks or soft spectra at the highest energies. We present a fully time-dependent NDSA-model in which we simultaneously solve the transport equation for cosmic rays and the hydrodynamical equations for the thermal plasma in 1-D under the assumption of spherical symmetry. We apply our model to remnants expanding in a uniform medium and show that the cosmic-ray gradient in downstream of the shock significantly can modify the downstream flow profile. This effect influences the evolution of the remnant as well as the compression ratio at the thermal sub-shock and thus the resulting particle spectra.

Speaker: Robert Brose (DESY)

Slides Brose_CrModifiedShocks.pdf

236 Production of non-thermal electrons at nonrelativistic perpendicular shocks of young supernova remnants

The injection problem is a key and still unresolved issue of diffusive shock acceleration theory. Electron injection mechanisms at high Mach-number nonrelativistic perpendicular shocks are under consideration here for parameters that are applicable to young SNR shocks. Using high-resolution large-scale two-dimensional fully kinetic particle-in-cell (PIC) simulations we explore the production of high-energy electrons in the shock transition. Tracing individual particles we in detail analyze the physics of the formation of non-thermal electron population. Ion reflection off the shock leads to the formation of magnetic filaments in the shock ramp, resulting from Weibel-type instabilities, and electrostatic Buneman modes in the shock foot. Electrons are accelerated via shock surfing acceleration (SSA) in the Buneman-instability region and undergo further scattering in the Weibel-instability region via a second-order Fermi-like process. The combination of these two processes leads to the formation of a non-thermal electron population, but their individual impact strongly depends on the Alfvenic Mach number and reduced ion-to-electron mass ratio. We discuss the resulting electron spectra and the relevance of our results to the physics of systems with real ion-to-electron mass ratio and fully three-dimensional systems.

Speaker: Dr Artem Bohdan (DESY)

Slides TeVPA_(august_2018)_(3).pptx

237 Cosmic ray transport simulations with CRPropa: Extensions and applications

Experimental observations of Galactic and extragalactic cosmic rays in the last decade challenge the theoretical description of both the sources and the transport of cosmic rays. The latest version of the publicly available simulation framework CRPropa 3.2 aims at a consistent solution of the cosmic-ray transport problem, including the production and propagation of secondary neutrinos and electromagnetic cascades. The Monte-Carlo based software is not only able to describe the transport of cosmic rays in a ballistic single-particle propagation but is also able to solve a transport equation. This combined approach will allow a consistent description of cosmic rays from the highest energies down to the TeV-range. This talk will summarize the latest extensions of the code, e.g. solving the transport equation, improved electromagnetic cascades, source targeting, cosmic-ray acceleration and many technical improvements. The transport of cosmic rays accelerated at the galactic termination shock is discussed as an example for these new features.

Speaker: Mr Lukas Merten (Ruhr-Universität Bochum)

Slides TeVPA2018_Merten.pptx

238 Cosmic Ray Acceleration and Propagation from Galactic Wind Shocks

Diffusive shock acceleration (DSA) at supernova remnant (SNR) shock fronts is thought to accelerate galactic cosmic rays (CRs) to energies below the knee, while an extragalactic origin is presumed for CRs with energies beyond the ankle. CRs with energies between $3 \times 10^{15}$ and $10^{18}$ eV, which we dub the ``shin," have an unknown origin. In this talk, I will outline our recent theoretical work on the acceleration and propagation of shin CRs generated at galactic wind shocks. Using the steady-state wind model developed by Bustard et al. 2016, combined with optimistic assumptions for the CR acceleration rate, we estimate the energies of CRs accelerated by galactic wind termination shocks both in starburst galaxies and our own Milky Way. Our results suggest that shin CRs can be accelerated within reasonable times at such sites; however, the production of ultrahigh energy CRs is somewhat disfavored. Using parameters for a possible wind in our own Galaxy, we then utilize the CRPropa propagation code to produce CR and neutrino spectra for CRs diffusing back to the galaxy in opposition of a galactic wind. We find the flux to be significant but below IceCube measurements and KM3NeT limits. Shocks produced closer to the Galaxy’s center, which are evident in time-dependent wind models, may provide a more significant CR source. (References: Bustard et al. 2017, ApJ; Merten, Bustard, et al. 2018, ApJ)

Speaker: Chad Bustard (University of Wisconsin - Madison)

Slides TeVPA2018_Chad_PDF.pdf

239 LIV limits from ultra high energy astrophysics

In this work, the photon horizon including LIV is studied by correcting the pair-production interaction of gamma-ray with the Cosmic Background Light. The derived scenarios are used to predict important changes in the propagation of photons with energy greater than 10 ^ 18 eV. We have computed the GZK photon flux on Earth for several ultra high energy cosmic ray source (UHECR) models and we compare them with the new upper limits of the photon flux obtained by the Pierre Auger Observatory to impose higher limits to the generic LIV coefficients of order n = 0, 1 and 2 in the astrophysical scenario which better describes the UHECR data.

Speaker: Dr Humberto Martínez-Huerta (IFSC - USP)

Slides LIV_HMH_TeVPa18.pdf

Dark Matter: 4

Chair 1: Louise Oakes | Chair 2: Nathan Kelley-Hoskins | Chair 3: Klaus Eitel | Chair 4: Dan Hooper | Chair 5: Daniele Gaggero | Chair 6: Michele Doro | Chair 7: Mónica Vázquez-Acosta

Conveners: Louise Oakes (Humboldt Universität zu Berlin), Prof. Marc Schumann (Univertity of Freiburg), Dr Miguel Sánchez-Conde (IFT UAM/CSIC)

240 Update on the EDELWEISS Dark Matter Search

The EDELWEISS collaboration is performing a direct search for WIMP dark matter in the mass range from 1 to 20 GeV/c2 using cryogenic germanium detectors equipped with a full charge and thermal signal readout. We present the most recent results and the currently ongoing program to reduce the experimental thresholds in order to gain sensitivity for low mass WIMPs. This comprises utilizing the Neganov -Luke effect in the EDELWEISS-LT program as well as increasing the discrimination of backgrounds with an improved ionization readout. New results and prospects for Axion-Like Particle dark matter searches will also be presented. Claudia Nones (CEA) or Klaus Eitel (KIT)

Speaker: Dr Klaus Eitel (Karlsruhe Institute of Technology)

Slides Eitel_TeVPA2018-EDELWEISS.pdf

241 Novel light dark matter signals in xenon direct detection experiments

Direct detection experiments that utilise xenon have proven to be most sensitive for heavy (>5 GeV) dark matter particles. In this talk, I'll explore signals that allow xenon experiments to probe the dark matter - nucleon cross section for dark matter particles down to ~100 MeV. These signals arise from electron or photon emission from the xenon atom after a collision with a light dark matter particle. This talk is based on arXiv:1702.04730 and arXiv:1711.09906.

Speaker: Dr Christopher McCabe (King's College London)

Slides mccabe_tevpa.pdf

242 Latest results of LUX dark matter experiment

The Large Underground Xenon (LUX) detector was a dual-phase xenon Time Projection Chamber with an active mass of 250 kg searching for Weakly Interacting Massive Particle (WIMP) dark matter via direct detection. It operated at the Sanford Underground Research Facility (SURF) in Lead, South Dakota from 2012 to 2016. LUX has published three previously world leading limits on the spin-independent cross section for the WIMP-nucleon scattering. Since the Fall of 2016 when the detector was dismantled, efforts have been focused on additional analyses with the existing science and calibration data sets. This talk will report results from several recent analyses and describes new work that improves our understanding of radiogenic backgrounds and detector performance.

Speaker: M. I. Lopes (on behalf of LUX Collaboration; University of Coimbra and LIP)

Slides LUXReview_TeVPA_2018_IsabelLopes.pdf

243 Bracketing the impact of astrophysical uncertainties on dark matter searches

The theoretical interpretation of dark matter experiments is hindered by uncertainties of the dark matter density and velocity distribution inside the Solar System. In order to quantify those uncertainties, we present a parameter that characterizes the deviation of the true velocity distribution from the Maxwell-Boltzmann form, and we then determine for different values of this parameter the most aggressive and most conservative limits on the dark matter scattering cross section with nuclei. This allows us to bracket, in a model independent way, the impact of the astrophysical uncertainties on the interpretation of null search results from direct detection experiments and/or neutrino telescopes.

Speaker: Andreas Rappelt (Technische Universität München)

Slides RappeltTeVPA.pdf

244 Dark matter searches with LUX-ZEPLIN (LZ)

LUX-ZEPLIN (LZ) is a second-generation dark matter experiment currently under construction. It will follow LUX in the 1480-m deep Sanford Underground Research Facility in South Dakota, with a projected sensitivity for the spin-independent cross section of $1.6\times10^{-48}~$cm$^{2}$ for a 40 GeV/c$^2$ mass Weakly Interacting Massive Particle (WIMP) after 1000 live-days exposure of a 5.6-tonne fiducial mass. Inside an ultra-low background titanium cryostat, a central liquid xenon time projection chamber contains a total active mass of 7 tonnes surrounded by a 2-tonne xenon skin detector. A gadolinium-loaded liquid scintillator and an instrumented water tank complete the detector setup. Extensive campaigns have been undertaken to ensure the experiment achieves its background goals by minimization of its radioactivity and optimization of its performance. An overview, the current project status and the experimental timeline will be presented.

Speaker: Dr Alfredo Tomas Alquezar (Imperial College London)

Slides TeVPA_Berlin_ATomas180829.pdf

245 Simple self-consistent prediction methods for the phase space of dark matter: from galactic dynamics to phenomenology

In the context of dark matter (DM) searches, it is crucial to quantify and reduce theoretical uncertainties affecting predictions of observables that depend on the DM velocity distribution, including event rates in direct searches, velocity-dependent annihilation rates, and microlensing event rates for DM compact objects. The well-known Eddington inversion formalism for the self-consistent reconstruction of the isotropic DM phase-space distribution from a galactic mass model allows one to go beyond the simplistic Maxwell-Boltzmann approximation or direct extrapolations from cosmological simulations, with limited technicalities. However, this method and its anisotropic extensions can be ill-defined depending on the DM and baryonic content of the galaxy of interest. In this presentation, I will discuss the validity range of the Eddington inversion methods from a theoretical perspective, as well as issues arising from accounting for the finite boundary of a galactic system. I will show how this impacts on observables relevant to DM searches. As an application, I will present very strong novel constraints on p-wave suppressed DM annihilation from positron data.

Speaker: Dr Thomas Lacroix (Laboratoire Univers et Particules de Montpellier)

Slides TeVPA_2018_TL.pdf

246 DarkSUSY 6: More than SUSY Dark Matter

We present a radically new version of the widely used DarkSUSY package, which allows to compute the properties of dark matter particles numerically. With DarkSUSY 6 one can accurately predict a large variety of astrophysical signals from dark matter, such as direct detection in low-background counting experiments and indirect detection through antiprotons, antideuterons, gamma-rays and positrons from the Galactic halo, or high-energy neutrinos from the center of the Earth or the Sun. For WIMPs, high-precision tools are provided for the computation of the relic density in the Universe today, as well as for the size of the smallest dark matter protohalos. Compared to earlier versions, DarkSUSY 6 introduces many significant physics improvements and extensions. The most fundamental new feature of this release, however, is that the code has been completely re-organized and brought into a highly modular and flexible shape. Switching between different pre-implemented dark matter candidates has thus become straight-forward, just as adding new – WIMP or non-WIMP – particle models or replacing any given functionality in a fully user-specified way. I provide a brief overview of the physics behind the computer package, along with the main structure and philosophy of this major revision of DarkSUSY.

Speaker: Prof. Torsten Bringmann (Oslo University)

Slides Bringmann_for_upload.pdf

Extragalactic Science: 2

Chair 1: Tova Yoast-Hull | Chair 2: Günter Sigl | Chair 3: Shigeo Kimura

Conveners: Dr DI MAURO MATTIA (Stanford University), Prof. Guenter Sigl (University of Hamburg), Prof. Kunihito Ioka (Yukawa Institute for Theoretical Physics, Kyoto University), Tova Yoast-Hull (Canadian Institute for Theoretical Astrophysics)

247 Characterizing the brightest gamma-ray flares of flat spectrum radio quasars

Almost 10 years of observations with the Fermi Large Area Telescope (LAT) have revealed extreme gamma-ray outbursts from flat spectrum radio quasars (FSRQs), temporarily making these objects the brightest gamma-ray emitters in sky. Yet, the location and mechanisms of the gamma-ray emission remain elusive. Here, we characterize the brightest flares of six FSRQs observed with the LAT. We find evidence for variability on timescales as short as minutes in all but one source, which suggests that extremely compact emission regions located at large distances from the central black hole are a common feature in FSRQs. We do not find any signs for gamma-ray absorption in the broad line region, which further further indicates that the gamma rays are produced away from the black hole by hundreds of gravitational radii. The gamma-ray light curves of these sources on different temporal scales provide us with a rich data set that can be compared to theoretical models of emission and particle cooling scenarios.

Speaker: Dr Manuel Meyer (Stanford University)

Slides mmeyer_fsrqs_fermi.pdf

248 On the cause of the extraordinary flare of CTA 102

In late 2016 and early 2017, the flat spectrum radio quasar CTA 102 (z=1.032) experienced an extraordinary phase of its existence. Starting in October 2016, over the course of two months the gamma-ray flux rose by a factor 50 and decreased again for 2 months to pre-flare levels. This long-term trend has been superposed by short, bright flares, which made CTA 102 one of the brightest gamma-ray sources in the sky despite its large cosmological distance. Simultaneously to the gamma-ray trend, the optical flux has increased by a factor 100, while the X-rays varied by a factor of 10 compared to pre-event observations. We explain the event by the ablation of a passing gas cloud by the jet. This model fits amazingly well the long-term trend and can also account for the short-term outbursts on top of that.

Speaker: Dr Michael Zacharias (TPIV, Ruhr-Univseristät, Bochum, Germany)

Slides Zacharias_CTA102_TeVPA18_v01.pdf

249 Intranight variability of VHE gamma-ray emission during the outburst of PKS 1510-089 in May 2016

PKS 1510-089 is one of only a handful of flat spectrum radio quasars detected in very high energy (VHE, E > 100 GeV) gamma rays. Since the first detection in 2009, despite showing strong variability in the optical and GeV range, no VHE gamma-ray variability could be claimed until a moderate 5-fold increase of the VHE gamma-ray flux was observed in 2015. In May 2016, a major VHE gamma-ray flare was observed from PKS 1510-089 by the H.E.S.S. and MAGIC telescopes. Within ~5h of observations the VHE gamma-ray flux changed by an order of magnitude showing short-term variability features for the first time. Despite a soft intrinsic spectrum and strong absorption in the extragalactic background light, the high flux of the source allowed us to measure the gamma-ray spectrum up to the energy of 0.7 TeV. We will report on the results of those observations as well as of the supporting observations performed in the optical and GeV range. We will also discuss possible explanations for the observed emission.

Speaker: Dr Julian Sitarek (University of Lodz)

Slides 201808_tevpa_pks1510_2016flare.pdf

250 H.E.S.S. observation of 3C 279 during optical and gamma-ray flares in 2017 and 2018

The FSRQ 3C 279 (z=0.536) is a well known bright variable blazar. In recent years it has undergone several luminous outbursts detected at all wavelengths. Here we highlight the results of H.E.S.S. observations of two types of events of different nature during the year 2017 and in January 2018. The first Target of Opportunity followed the external trigger from the ATOM optical telescope that observed the source during a historical maximum in the R band, with a peak brightness of 13 magnitudes. Interestingly, this high optical flux was not mirrored at gamma-ray energies, which can place strong limits on the emission mechanism of this “orphan” flare. The 2018 observations were instead a reaction to a Fermi-LAT trigger for the second brightest flare ever seen from this source. We report a strong detection at very high energies during the decay phase of the Fermi-LAT flare. These events are presented in a multi-wavelength perspective in the context of the active phase that this source is undergoing since early 2017, with repeated outbursts.

Speaker: Carlo Romoli (Max Planck Institute or Nuclear Physics)

Slides 3c279_tevpa2018_v3.pdf

251 New results on the anomalous transparency of the Universe for very-high-energy gamma rays

Unphysical distance dependence in convex features of deabsorbed blazar spectra (upward breaks), reported in 2014, suggested incorrect model of absorption of E>100 GeV gamma rays due to e+e- pair production on the extragalactic background light (EBL). We present and interpret results of the new study aimed to constrain EBL in the same approach, making use of an updated clean source sample, new gamma-ray data and most recent absorption models.

Speaker: Prof. Sergey Troitsky (INR, Moscow)

Slides gamma-TeVPA2018.pdf

252 TeV blazars and the transparency of the Universe

The Universe is expected to be opaque for gamma rays with TeV energies. However several distant blazars have been observed in TeV region. One possible solution to this puzzle is to assume that the same sources emit cosmic rays towards the Earth and the gamma rays observed are products of line of sight cosmic ray interactions. We examine viability of this scenario in the context of possible cosmic ray and secondary electromagnetic cascade deflections by the extragalactic magnetic field and the large scale structure magnetic field. To test the hypothesis we use recent estimates of filament distribution in the Universe and perform Monte Carlo simulations of primary and secondary particle propagation.

Speaker: Dr Mikhail Kuznetsov (INR RAS, Moscow)

Slides talk.pdf

253 LIV Signatures in EBL absorption and Compton scattering

At energies approaching the Planck energy scale $10^{19} GeV$, several quantum-gravity theories predict that familiar concepts such as Lorentz (LIV) symmetry can be broken. Such extreme energies are currently unreachable by experiments on Earth, but for photons traveling over cosmological distances the accumulated deviations from the Lorentz symmetry may be measurable using the Cherenkov Telescope Array (CTA). To study the spectral hardening feature observed in some VHE gamma-ray blazars, we calculate the reduction of the EBL gamma-gamma opacity due to the existence of underdense regions along the line of sight to VHE gamma-ray sources and we compared with the possibility of a LIV signature. Considering the LIV effect, we found that the cosmic opacity for VHE gamma rays with energy more than 10 TeV can be strongly reduced. I will further discuss the impact of LIV on the Compton scattering process, and how future CTA observations may open an exciting window on studies of the fundamental physics.

Speaker: Mr Hassan Abdalla (North-West University)

Slides 1745_Hassan_Abdalla_TeVpa.pdf

Gamma Rays: 5

Chair 1: Stefan Ohm | Chair 2: Ruben Lopez-Coto | Chair 3: Sara Buson | Chair 4: Felicia Krauss | Chair 5: Francesco Longo | Chair 6: David Sanchez | Chair 7: Konstancja Satalecka

Conveners: Dr Ruben Lopez-Coto (INFN Padova), Dr Sara Buson (NASA-GSFC), Mr Stefan Ohm (DESY, Zeuthen)

254 The Galactic Centre region in gamma rays

The Galactic Center (GC) hosts a Super-Massive Black Hole (SMBH) of 4*10^6 Msun, Sgr A*, which has apparently experienced phases of quasar activity in the past and might accelerate particles up to very high energy. The inner 150 pc also harbor intense star formation activity and many Supernova Remnants and Pulsar Wind Nebulae which must also be the site of sustained particle acceleration. At GeV energies, the Fermi-LAT gamma-ray data show huge outflows extending 10 kpc above the Galactic disk pervaded by energetic particles, the so-called Fermi bubbles, but also several yet unidentified sources close to the GC. More recently, an additionnal 10 deg scale excess of gamma-ray emission peaking at few GeVs has been claimed. At higher energy, multiple observations by Imaging Atmospheric Cherenkov Telescopes (IACTs) array such as MAGIC, VERITAS and H.E.S.S. have shown the proeminent contribution of two point sources, HESS J1745-2901 compatible with the position of SgrA*, and HESS J1747-281 associated with G0.9+0.1, and a hard diffuse emission correlated with the dense matter distribution of the Central Molecular Zone over more than 1° in longitude. We will review these large amount of results collected during more than 10 years of intense study of the GC in gamma-ray, and discuss the possible origin of the observed emissions as well as their connection with the local known accelerators and the cosmic-ray population in the Galaxy.

Speaker: Dr ANNE LEMIERE (APC)

Slides alemiere_TeVPA2018.pdf

255 Pevatron at the Galactic Center: Multi-Wavelength Signatures from Millisecond Pulsars

Diffuse TeV emission has been observed by H.E.S.S. in the Galactic Center region, in addition to the GeV gamma rays observed by Fermi. We propose that a population of unresolved millisecond pulsars located around the Galactic Center, suggested as possible candidates for the diffuse Galactic Center excess observed by Fermi, accelerate cosmic rays up to very high energies, and are thus also responsible for the TeV excess. We model analytically the diffusion of these accelerated protons and their interaction with the molecular clouds, producing gamma rays. The spatial and spectral dependences of the gamma rays produced can reproduce the H.E.S.S. observations, for a population of $\sim 10^4-10^5$ millisecond pulsars above the cosmic-ray luminosity $10^{34}\,{\rm erg\,s}^{-1}$, with moderate acceleration efficiency. More precise measurements at the highest energies would allow us to constrain the properties of the pulsar population, such as the magnetic field or initial spin distributions.

Speaker: Ms Claire Guépin (Institut d'Astrophysique de Paris)

Slides TEVPA_2018_CG_GRs.pdf

256 The Fermi GeV Excess as a Tracer of Stellar Mass in the Bulge: Results with SkyFACT

A persistent excess of gamma rays measured with the Fermi-LAT has been found towards the center of the Galaxy, typically referred to as the Galactic Center Excess (GCE). While its existence is well established, its nature and origin are still debated. While a simple but exotic origin for the GCE could be the annihilation of dark matter, other astrophysical origins, such as emission from millisecond pulsars, are currently more plausible. However, most gamma-ray analyses of the inner Galaxy suffer from incomplete background and foreground modeling that make it difficult to extract the morphology of the GCE and also formally yield poor fits to the data. In order to understand the effects of modeling systematics on the GCE, we use an analysis tool called SkyFACT, or Sky Factorization with Adaptive Constrained Templates. In contrast to standard approaches, SkyFACT combines techniques from image reconstruction and template fitting, and makes use of a likelihood that is regularized via the maximum entropy method to efficiently handle large numbers of nuisance parameters. We apply this tool to the inner Galaxy to robustly fit the spectrum and morphology of the GCE. We find that a model for the boxy bulge is strongly preferred over dark matter templates, and that the GCE luminosity scales with the stellar mass contained in this boxy bulge.

Speaker: Emma Storm (University of Amsterdam)

Slides Storm_TeVPA2018.pdf

257 Gamma-ray emission at the base of the Fermi bubbles

The Fermi bubbles (FBs) are two large lobes observed in gamma rays up to 55 degrees above and below the Galactic center. Although the FBs were discovered 8 years ago, their origin is still unknown. Even the process of production of the gamma rays: leptonic inverse Compton scattering or interactions of hadronic cosmic rays with gas, is not yet known. Answering the questions of the origin of the FBs and the nature of the gamma-ray emission has turned out to be remarkably difficult. Important clues about the origin of the FBs can be obtained from looking at the FBs near the Galactic plane. Recent analysis has shown that the residual emission at the base of the FBs (after subtraction of the foreground and background emission) is brighter and extends to higher energies than the spectrum of the FBs at high latitudes. In the talk, I will discuss a new analysis of the gamma-ray emission at the base of the FBs using 8 years of Pass 8 Fermi-LAT data. We confirm that the emission at the base of the FBs has a hard spectrum without a cutoff up to 1 TeV and a greater intensity than at high latitudes. I will discuss possible interpretations of this emission in terms of the leptonic and hadronic models as well as the prospects for detectability of the emission by Cherenkov and neutrino telescopes.

Speaker: Dr Dmitry Malyshev (Erlangen Center for Astroparticle Physics)

Slides Malyshev_Bubbles_TeVPA_2018.pdf Malyshev_Bubbles_TeVPA_2018.pptx

258 The Fermi bubble study with future gamma ray experiments

The Fermi bubbles (FBs) are two giant gamma-ray lobes above and below the Galactic center. Their origin is not clear yet and both hadronic and leptonic models are currently allowed. In the hadronic model, the acceleration of protons and/or nuclei and their subsequent interactions with gas in the bubble volume can produce the observed gamma rays and high-energy neutrinos as counterparts. The detection of neutrinos can discriminate between a hadronic and a leptonic origin of the FB. Recently HAWC reported no gamma ray excess from the northern bubble at high latitude, which agrees with Fermi measurements. However, due to the limitation of the searching region and energy at HAWC, the hadronic model is not constrained for the central region of the FB. Here we present a sensitivity study of Cherenkov Telescope Array (CTA) to our FB hadronic model with the morphological analysis and classical on/off analysis based on the realistic CTA deep central and extended survey. As a complement, and for comparison, we study the detectability of the FBs with the future ground-based Cherenkov detector LHAASO as well.

Speakers: Ms Lili Yang (University of Nova Gorica), Prof. Soebur Razzaque (University of Johannesburg)

Slides TeVPA_Yang.pdf

259 Bayesian Model Comparison and Analysis of the Galactic Disk Population of Gamma-Ray Millisecond Pulsars

Global properties of the almost one hundred millisecond pulsars (MSPs) detected in gamma-rays by the Fermi Large-Area Telescope remain relatively unknown due to multiple large uncertainties. I present here a extensive Bayesian analysis of both the spatial distribution and luminosity function simultaneously. Distance uncertainties, arising from errors in the parallax measurement or Galactic electron-density model, are marginalized over. We provide a public Python package for calculating distance uncertainties to pulsars derived using the dispersion measure by accounting for the uncertainties in Galactic electron-density model YMW16. We use multiple parameterizations for the MSP population and perform Bayesian model comparison, finding that a broken power law luminosity function with Lorimer spatial profile are preferred over multiple other parameterizations used in the past. Finally, I show how these results impact the MSP interpretation of the Galactic Centre Excess.

Speaker: Mr Thomas Edwards (GRAPPA, University of Amsterdam)

Slides Pulsars_ModelComparison_Edwards.pdf

260 Connecting IceCube neutrinos to Galactic TeV photons

A signal of high-energy extraterrestrial neutrinos from unknown source(s) was recently discovered by the IceCube experiment. Neutrinos are always produced together with γ-rays, but the γ-ray flux from extragalactic sources is suppressed due to attenuation in the intergalactic medium. We report a γ-ray excess at high Galactic latitudes starting at energies 300 GeV in the data of the Fermi telescope. We show that the multi-TeV γ-ray diffuse emission has spectral characteristics at both low and high Galactic latitudes compatible with those of the IceCube high neutrino signal in the same sky regions. This suggests that these γ-rays are the counterpart of the IceCube neutrino signal, implying that a sizable part of the IceCube neutrino flux originates from the Milky Way. We argue that the diffuse neutrino and γ-ray signal at high Galactic latitudes originates either from previously unknown nearby cosmic ray "PeVatron" source(s), an extended Galactic CR halo or from decays of heavy dark matter particles.

Speaker: Michael Kachelriess (NTNU)

Slides tevpa18.pdf

Dinner

Thursday, 30 August

Particle Physics

Chair: David Berge

261 LHC results

Follows soon.

Speaker: Beate Heinemann (DESY and Freiburg University)

Slides 2018_TevPA.pdf

262 LHC BSM results

Follows soon.

Speaker: JiJi Fan (Brown University)

Slides TeVPA_2018_Fan.pdf

263 Neutrino Physics: Status and Perspectives

We discuss the current status of theoretical and experimental neutrino physics, focusing on ways in which neutrinos can help to answer some of the most fundamental questions in particle physics and astrophysics. Topics covered include neutrino oscillations, neutrino masses, neutrino astronomy, and connections between the neutrino sector and dark matter.

Speaker: Joachim Kopp (University of Mainz & CERN)

Slides neutrino-physics.pdf

10:30 Coffee Break

Cosmic-rays: 2

Chair 1: Kathrin Egberts | Chair 2: Christoph Pfrommer

264 CR propagation in our galaxy

I will present an overview of recent developments in numerical modelling of CR transport in our Galaxy. Corresponding numerical models aim at reproducing CR spectra and also diffuse gamma-ray emission from the Galaxy. For these numerical models we witness a transition from two-dimensional azimuthally symmetric models to those that use a more realistic description of our Galaxy. Focusing on results computed with the CR propagation code Picard, I will address the new physics that can be incorporated in such three-dimensional models. This includes, e.g., the impact of localised sources and also the possibility to investigate the effect of anisotropic diffusion with respect to the local magnetic field.

Speaker: Ralf Kissmann (Universität Innsbruck)

Slides TalkTeVPA2018.pdf

265 Antimatter cosmic rays in the era of precision measurements

Antimatter cosmic rays have become a fashionable tool to probe for the presence of dark matter particles in the Milky Way. Should these species exist, they would annihilate or decay, hence producing positrons and anti-nuclei which would distort the conventional signals expected at the Earth. But are these backgrounds well known? There’s the rub. Regardless of the dark matter problem, anti-matter is produced in the form of secondary cosmic-rays through the interaction of high-energy protons and helium nuclei on the interstellar medium. A precise calculation of the corresponding fluxes at the Earth is paramount to unravel any exotic signal. I will discuss how these backgrounds are estimated and present various reasons for which these predictions are still less precise than desired. The periodical announcement of the discovery of dark matter in the antiproton signal will illustrate my purpose. I will conclude with the search for anti-helium nuclei.

Speaker: Prof. Pierre SALATI (Laboratoire d'Annecy-le-Vieux de Physique Théorique LAPTh @ USMB)

Slides TeVPA_180830_salati.pdf TeVPA_180830_salati.pptx

266 Particle acceleration via magnetic reconnection

Follows soon.

Speaker: Lorenzo Sironi (Columbia University)

Slides sironi_tevpa18.pdf

12:30 Lunch Break

Cosmic Rays: 5

Chair 1: Don Ellison | Chair 2: Denise Boncioli | Chair 3: Andrew Taylor | Chair 4: Daniele Gaggero |
Chair 5: Tony Bell | Chair 6: Markus Ahlers

Conveners: Andrei Bykov (Ioffe Physico-Technical Institute), Dr Sabrina Casanova (IFJ PAN &amp; MPIK HD), Dr denise boncioli (DESY)

267 Stochastic cosmic ray sources and the TeV break in the all-electron spectrum

Despite significant progress over more than 100 years, no cosmic ray accelerator has been unambiguously identified as the source of the locally measured flux. High-energy electrons and positrons are of particular relevance in the search for sources as radiative energy losses constrain their propagation to distances of about 1 kpc. At the highest energies, the measured spectrum is dominated and shaped by only a few sources whose properties can likely be inferred from the fine structure of the spectrum. Ignoring the stochasticity of nearby sources leads to models that cannot fit the data at energies currently accessed by experiments like AMS-02, CALET, DAMPE, Fermi-LAT, HESS and ISS-CREAM. We start by critically assessing the reliability of using catalogues of known sources to model the electron-positron flux. Next, we present the results from a large suite of Monte Carlo simulations for the electron-positron flux based on a statistical ensemble of sources. This allows assessing the statistical compatibility of the models with the measurements. Specifically, we quantify the non-Gaussian fluctuations due to the stochasticity of sources in a realistic propagation setup. For the first time, we also consider the correlations of the measured flux in different energy bins, which allows differentiating astrophysical source models from exotic explanations, like dark matter. We conclude that the spectral break observed in the all-electron spectrum by HESS and recently by DAMPE is fully compatible with a distribution of astrophysical sources like supernova remnants.

Speaker: Philipp Mertsch (TTK, RWTH Aachen University)

Slides Mertsch_TeVPA2018.pdf

268 Local emission of cosmic ray electrons: multi-messenger constraints

The inclusive flux of cosmic electrons and positrons is now known with unprecedented precision up to few tens of TeV. Very recent data from AMS-02, DAMPE, CALET, FERMI and HESS suggest that the flux starts deviating from a single power law at TeV energies, with the presence of a break at around 1 TeV. In addition, new stringent upper bounds on the dipole anisotropy of the inclusive flux have been presented from Fermi-LAT. We present a multi-messenger study of the emission from local Galactic sources, namely Supernova Remnants (SNRs). For the first time, we quantify the constraints imposed by the dipole anisotropy upper bounds on the properties of nearby known SNRs. We find a multi-component model that is compatible with the radio fluxes from Vela YZ and Cygnus Loop SNRs, explains the electron and positron flux measurements from five experiments and the dipole anisotropy data.

Speaker: Silvia Manconi (University of Turin and INFN Turin)

Slides Manconi_tevpa18.pdf

269 The High-Energy End of the Cosmic-Ray Electron Spectrum

Multi-TeV cosmic-ray electrons carry unique information about local accelerators because of their severe radiative energy losses and the associated short propagation distances. The very low fluxes and the large background of hadronic cosmic rays however impose severe challenges to both space-born and ground-based measurements. The next generation satellite experiments are just starting to probe this energy regime. They will still need a couple of years to gain the statistics needed for precision measurements. Ground-based instruments with their five orders of magnitude larger effective collection areas on the other hand accumulate the necessary statistics easily and are ideally suited for measurements in this energy range. Their indirect detection of cosmic-ray electrons however requires a superb separation of the excessive hadronic background and is therefore prone to systematic errors. Recent developments allow now for the first time a measurement of the cosmic-ray electron spectrum up to 20 TeV, and provide at the same time a significant reduction of the associated systematic uncertainties. This contribution will present and discuss the latest H.E.S.S. measurement of the cosmic-ray electron spectrum.

Speaker: Dr Daniel Kerszberg (IFAE-BIST)

Slides Talk_TeVPA2018_Kerszberg.pdf

270 Interstellar electron and positron spectra from MeV to TeV energies

Electrons and positrons play a special role among cosmic ray (CR) species. Most strikingly, their strong energy losses in the Galactic magnetic and radiation fields severely limit their propagation distances. Therefore electrons and positrons offer invaluable insights into the local properties of CR acceleration and propagation. In this talk we present our model for their interstellar spectra over a wide energy range extending from the MeV to the TeV domain. We illustrate how the underlying parameters can be efficiently constrained by exploiting different experimental observations, including both direct observations of the spectra (at Earth and at the heliopause) and measurements of the diffuse synchrotron emission generated by CR leptons as they propagate through the magnetic field of the Galaxy. For the first time, we consider recent time-dependent observations at GeV energies by AMS-02 and estimate heliospheric modulation in an extension of the force-field model. What emerges is a complex picture of the interstellar electron and positron spectra that must be shaped by a number of transport processes beyond the simplest models.

Speaker: Dr Andrea Vittino (TTK, RWTH Aachen)

Slides Vittino_TeVPA_2018.pdf

271 Contribution of Geminga and Monogem Pulsar Wind Nebulae to the positron excess

An excess of cosmic positrons above 10 GeV with respect to the spallation reaction of cosmic rays (CRs) with the interstellar medium has been measured by Pamela, Fermi-LAT and with unprecedented precision by the AMS-02 experiment. Various interpretations have been invoked to interpret this excess, such as production from supernova remnants, pulsar wind nebulae (PWNe) and dark matter. A dominant contribution from dark matter is ruled out by the bounds found in gamma rays and other indirect searches. Models where supernova remnants produce secondary CRs struggle to explain the observed CR fluxes by AMS-02. Finally, severe constraints for a significant PWN contribution comes from the detection of very high-energy emission from Monogem and Geminga PWNe by Milagro and HAWC experiment. In this talk we will present the constraints found for the contribution of these PWNe to the positron excess combining Milagro and HAWC data with measurements from the Fermi LAT for the first time. We will show that using gamma-ray data from the LAT is of central importance to provide a precise estimate for a PWN contribution to the cosmic positron flux. We will also present the most promising energies to detect a signal of synchrotron emission for positrons emitted by PWNe and will discuss the prospects of detecting this signature with current or future experiments.

Speaker: Dr Mattia DI MAURO (STANFORD UNIVERSITY)

Dark Matter: 5

Chair 1: Louise Oakes | Chair 2: Nathan Kelley-Hoskins | Chair 3: Klaus Eitel | Chair 4: Dan Hooper | Chair 5: Daniele Gaggero | Chair 6: Michele Doro | Chair 7: Mónica Vázquez-Acosta

Conveners: Louise Oakes (Humboldt Universität zu Berlin), Prof. Marc Schumann (Univertity of Freiburg), Dr Miguel Sánchez-Conde (IFT UAM/CSIC)

272 Status of Dark mater searches with IceCube

The IceCube Neutrino Observatory at the South Pole is the world's largest neutrino telescope in operation. It instruments a kilometer cube of ice with more than 5000 optical sensors that detect the Cherenkov light emitted by particles produced in neutrino-nucleon interactions. Being sensitive to a wide range of neutrino energies, from a few GeV to PeVs, its physics program is extremely rich. The talk will concentrate on the searches for dark matter gravitationally accumulated at the center of the Sun, the Earth or the galactic center, where dark matter self-annihilations or decay to standard model particles can produce a detectable flux of neutrinos. The latest limits from IceCube on the dark matter-nucleon cross section, on the dark matter self-annihilation cross section and on dark matter lifetime, will be presented.

Speaker: Dr Carlos de los Heros (Uppsala University)

Slides delosheros_TeVPA2018.pdf

273 Latest results on dark matter searches using the H.E.S.S. telescopes

In this talk, we present the latest results on dark matter searches using the High Energy Stereoscopic System (H.E.S.S.) located in Namibia. Dark matter is searched for looking for high-energy gamma-ray events in the most promising regions of the sky. Dark matter particles could self-annihilate and produce high-energy gamma rays, either as spectral lines or as continous spectrum. The inner region of the Milky Way halo harbors a large amount of dark matter, and we report a search for the annihilation of dark matter particle in this region. Nearby dwarf spheroidal galaxies, which are satellites of the Milky Way, are the most dark matter dominated objects in the Universe and are not expected to be the site of non-thermal high-energy gamma-ray emission or intense star formation, and are thus promising candidates for indirect dark matter searches. We present the latest results for the dark matter searches from the H.E.S.S. observation of these objects. Alternatively, dark matter could reveal indirectly through the measure of the cosmic-ray electron and positron energy spectrum, and we present its latest measurement by H.E.S.S. up to 20 TeV energies.

Speaker: Dr Vincent Poireau (LAPP/CNRS)

Slides poireau.pdf poireau.pptx

274 On the verge of the next generation TeV dark matter searches

Using tens of telescopes and cutting-edge design, the Cherenkov Telescope Array (CTA) project will probe high and very high-energy gamma rays with two independent installations in both hemispheres. With 5-20 times more sensitivity, depending on the energy, than current instruments such as MAGIC, HESS and VERITAS, as well as improved energy and angular resolutions, CTA will be an outstanding instrument. For dark matter searches, the CTA performance will mark the start of a new epoch, with an instrument sensitive to the dark matter thermal annihilation rate at the TeV regime. However, the definition of the best strategy in terms of target choice, exposure and priority, is still a matter of debate. Furthermore, it is important to discuss what external inputs CTA may need to optimise the program. This report will summarise expectations and plans for CTA dark matter searches in a few years from now.

Speaker: Dr Michele Doro (UAB)

Slides doro_2018_tevpa.pdf

275 Unassociated Gamma-ray Sources as Targets for Indirect DM Detection with Fermi-LAT

We perform a search of Dark Matter (DM) subhalo candidates among unassociated catalogued sources present in the most recent Fermi-LAT point-source catalogs (3FGL, 2FHL and 3FHL). These LCDM-predicted DM subhalos are promising candidates for gamma-ray emission from WIMP annihilation in the LAT energy band. Several selection criteria are applied, based on the expected properties of the DM-induced emission from DM subhalos, which allow us to significantly reduce the list of potential candidates. Then, by characterizing the LAT sensitivity to DM subhalos and by comparing our remaining candidates' list to state-of-the-art predictions based on the Via Lactea II N-body cosmological simulation, we place conservative and robust constraints on the annihilation cross section as a function of DM particle mass. These complementary constraints are comparable to those obtained from LAT observations of dwarf galaxies.

Speaker: Mr Javier Coronado-Blázquez (IFT UAM-CSIC)

Slides CoronadoBlazquez_TeVPa18_DM.pdf

276 Searching for Dark Matter Annihilation in the Milky Way Halo at High Latitudes

The Milky Way halo is the brightest source of dark matter annihilation on the sky. Indeed, the potential strength of the Galactic dark matter signal can supersede that expected from dwarf galaxies and galaxy groups even in regions away from the Inner Galaxy. We present the results of a search for dark matter annihilation in the smooth Milky Way halo for $|b| > 20^\circ$ and $r < 50^\circ$ using 413 weeks of Fermi Pass 8 data within the energy range of $\sim$0.8—50 GeV. We exclude thermal dark matter with mass below $\sim$70 GeV that annihilates to $b\bar{b}$ at the 95% confidence level using the p6v11 cosmic-ray foreground model, providing the strongest limits on the annihilation cross section in this mass range. These results exclude the region of dark matter parameter space that is consistent with the excess of $\sim$GeV photons observed at the Galactic Center for the $b\bar{b}$ annihilation channel and, for the first time, put the $\tau^+\tau^-$ explanation under tension. We explore how these results depend on uncertainties in the foregrounds by varying over a set of reasonable models.

Speaker: Laura Chang (Princeton University)

Slides TeVPA2018_Chang.pdf

277 Probing the sensitivity of the Cherenkov Telescope Array to Dark Matter in the Galactic Center

Revealing the nature of dark matter is one of the most riveting open tasks of modern astronomy and cosmology. To this end, observing and analyzing high-energy gamma-rays provides a promising and highly-effective tool to constrain the properties of dark matter particles. Being currently in its pre-construction phase, the Cherenkov Telescope Array (CTA) will soon observe the high-energy gamma-ray sky in the 20 GeV - 300 TeV energy range. Thus, it will open the possibility to explore the parameter space of heavy dark matter (above 100 GeV) with unprecedented sensitivity. One of the main targets for searches for signals of dark matter annihilation or decay is the center of our Galaxy. Due to its lower energy threshold and significantly larger effective area when compared to the current generation of ground-based Cherenkov telescopes, CTA is expected to be sensitive to diffuse astrophysical emission which is present in that region. In this talk, we present the status of the collaboration effort to estimate the sensitivity of CTA to various diffuse gamma-ray components in the surroundings of the Galactic Centre. Moreover, based on the astrophysical emission observed with the Fermi-LAT and the HESS telescope, we report on the impact of these diffuse astrophysical emission backgrounds on dark matter searches and suggest promising data analysis and observational strategies for the upcoming CTA data.

Speaker: Mr Christopher Eckner (University of Nova Gorica)

Slides DM_at_GC_TeVPA_2018_ECKNER.pdf

Extragalactic Science: 3

Chair 1: Tova Yoast-Hull | Chair 2: Günter Sigl | Chair 3: Shigeo Kimura

Conveners: Dr DI MAURO MATTIA (Stanford University), Prof. Guenter Sigl (University of Hamburg), Prof. Kunihito Ioka (Yukawa Institute for Theoretical Physics, Kyoto University), Tova Yoast-Hull (Canadian Institute for Theoretical Astrophysics)

278 Electromagnetic cascades from blazars

Electromagnetic cascading of TeV-band gamma-ray emission from distant blazars is a means to investigate the amplitude of magnetic field in the voids of intergalactic space. The flux of cascade emission from some objects is weaker than it should be, leaving two interpretation. The magnetic field may be strong enough to deflect the electron-positron pairs out of the line of sight. Alternatively plasma instabilities might drain the energy of the pairs. We present the current state of research and the most recent results, indicating that plasma instabilities in most cases cannot provide sufficiently strong energy losses. This leaves intact the evidence for pG magnetic fields in cosmic voids.

Speaker: Martin Pohl (DESY)

Slides PairCascadesVCM.pdf

279 CHIME and Fast Radio Bursts

Fast Radio Bursts (FRBs) are mysterious radio transients that occur at a prodigious rate of $\approx 10^3$ events per day above fluences of 1 Jansky-ms in the entire sky. Arriving from cosmological distances ($\sim$Gpc), FRBs show potential to be novel probes of cosmological parameters, the ionized baryon distribution, and the magnetic fields around and between galaxies. We do not know the origins of these bursts and a plethora of FRB models have been proposed but the tests of these models are observationally limited by the small heterogeneously assembled sample of FRBs. The Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) project at the Dominion Radio Astrophysical Observatory is designed to search a 200 deg$^2$ field of view for Fast Radio Bursts between 400–800 MHz with an expected FRB detection rate of between 1–10 FRBs/day which will lead to a large, well understood sample of FRBs. The CHIME/FRB backend is designed to detect and characterize FRBs in real time in 1024 independent beams on the sky and disseminate detection information for further multiwavelength follow up. I will discuss the design, ongoing commissioning and validation of CHIME/FRB, and future plans.

Speaker: Dr Shriharsh Tendulkar (McGill University)

Slides tevpa_chimefrb_spt_2018.pdf tevpa_chimefrb_spt_2018.pptx

280 Detection of virial shocks in Fermi-LAT galaxy clusters

Galaxy clusters are thought to grow by accreting mass through large scale, strong yet elusive, virial shocks. These collisionless shocks are thought to accelerate relativistic electrons, generating a spectrally-flat leptonic virial ring. However, with the exception of a VERITAS signal from the Coma cluster, attempts to detect virial rings have all failed. By stacking and rescaling Fermi-LAT data at 1-100GeV for the 112 most massive, high latitude, extended clusters we identify (at the 5.9 sigma confidence level) a bright, spectrally flat gamma-ray ring at the expected radius. This indicates that ~0.6% (with an uncertainty factor ~2) of the thermal energy is deposited in relativistic electrons over a Hubble time. This detection is confirmed using two multi messenger analyses of individual clusters: (1) A combined VERITAS (~220GeV), LAT and ROSAT R1 (~0.2keV) elliptical signal in Coma. (2) Planck SZ pressure near the virial radius, coincident with a LAT gamma-ray excess in Coma, A2319, and A2142. This results validate the shock paradigm, calibrate its parameters, and indicate that such shocks significantly contribute to the diffuse extragalactic gamma-ray and radio backgrounds.

Speaker: Mr Ido Reiss (Ben Gurion University of the Negev)

Slides Reiss_TeVPA2018.pdf

281 Gamma-ray bright young radio galaxy PMN J1603−4904

PMN J1603−4904 is only the second confirmed young radio galaxy (compact symmetric object) that has been detected with *Fermi*-LAT. These objects, which may transition into larger radio galaxies, are a stepping stone to understanding AGN and jet evolution. It is not clear how they can produce high-energy γ rays. We present multiwavelength observations, including a spectral energy distribution (SED) and a variability analysis. We obtained a Chandra observation to investigate source confusion, as this source is at a low Galactic latitude. Due to its hard LAT photon index, this source might be a TeV emitter and a potential target for the Cherenkov Telescope Array.

Speaker: Dr Felicia Krauss (GRAPPA/API, UvA)

Slides tevpa18_krauss.pdf

282 First detection of VHE gamma-ray signal from the FSRQ TON 0599

TON 0599 (z=0.7247) is the latest addition to a limited club of flat spectrum radio quasars (FSRQs) detected in very high energy (VHE, E > 100 GeV) gamma rays. Its redshift makes it the third farthest source, filling the gap in the redshift distribution of the VHE gamma ray emitters. It was detected for the first time with the MAGIC telescopes on 2017/12/15. The observations were triggered by hardening of the high energy (HE, E > 100 MeV) gamma-ray spectrum observed with Fermi-LAT. During 1 hour of observation with the MAGIC telescopes the flux reached about 40 per cent of the Crab Nebula flux above 80 GeV. The observations continued until 2017/12/29, witnessing gradual decrease of the flux. The spectrum in VHE gamma rays connects smoothly to the spectrum in HE obtained from simultaneous observations with Fermi-LAT. The joint spectrum shows sudden drop above about 8 GeV, which may suggest a strong absorption of VHE gamma rays within the source. In addition, we were able to follow the spectral evolution during the fading phase of the flare. We round the multiwavelength picture with observations in optical, IR, and radio bands acquired by the WEBT collaboration during the whole 2017-2018 optical observing season, from November to May.

Speaker: Dr Tomislav Terzić (University of Rijeka, Department of Physics)

Slides TON0599_TeVPA2018_TTerzic.pdf

Particle Physics: 2

Chair 1: Anatoli Fedynitch | Chair 2: Florencia Canelli

Conveners: Dr Anatoli Fedynitch (DESY), Prof. Florencia Canelli (University of Zurich), Pedro Machado (FNAL)

283 Forward physics with CASTOR and TOTEM at CMS

Many limitations in understanding important aspects of hadron collisions become most visible in the forward phase space at colliders. This is where the contributing physics is most soft, however, at the same time the energy transport is by far largest. This is why this region is in particular important for astroparticle physics. The CASTOR calorimeter at CMS has performed a series of measurements up to 13TeV. In this presentation we review the data and draw conclusions on the model performance and potential impact on understanding of hadron collisions. Furthermore, also the combined measurements of TOTEM+CMS are presented and discussed.

Speaker: Ralf Ulrich (Karlsruhe Institute of Technology)

Slides RalfUlrichTeVPA18.pdf

284 Cosmic ray related measurements from LHCb

The LHCb experiment has the unique possibility, among the LHC experiments, to be operated in fixed target mode using its internal gas target. The energy scale achievable at the LHC and the excellent detector capabilities for vertexing, tracking and particle identification allow a wealth of novel measurements of great interest for cosmic ray physics. In particular, using a helium target, the first measurement of antiproton production in proton-helium collisions was achieved using a 6.5 TeV proton beam,in the antiproton energy range 12-110 GeV/c. The results are particularly relevant to the interpretation of the recent accurate measurements of the antiproton content in cosmic rays.

Speaker: Giacomo Graziani (INFN Firenze)

Slides graziani_pHeLHCb_ICRC.pdf

285 Searches for dark matter (ATLAS and CMS)

Follows soon.

Speaker: Caterina Doglioni (Lund University)

Slides 20180827_Doglioni_TeVPA.pdf

286 Searches for long-lived particles (ATLAS and CMS)

Follows soon.

Speaker: Todd Adams (Florida State University)

Slides LHCLLPAdamsTeVPA2018v2.pdf

287 Searches for low and high mass resonances (ATLAS and CMS)

Follows soon.

Speaker: Saverio D’auria (University of Glasgow)

Slides Dauria-TeVPa-2018-ATLAS-CMS-Resonances.pdf

288 The search for neutrinoless double beta decay with a half-life beyond 10$^{26}$ yr with the GERDA experiment

The GERDA experiment searches for neutrinoless double beta decay of $^{76}$Ge. A discovery of this hypothetical decay would imply the Majorana nature of neutrinos and violation of lepton number conservation. To find this decay, with a half-life beyond 10$^{25}$ yr, gamma-ray spectrometers made from enriched $^{76}$Ge are operated directly immersed in liquid argon. Instrumenting the argon-filled cryostat with photosensors, scintillation light enables vetoing external background to push the background level below 10$^{-3}$ cts/(keV kg yr). Combined with the high energy resolution of germanium detectors, the sensitivity of GERDA will not be limited by background beyond an exposure of 100 kg yr. With a major data release this year, the exposure has now reached almost 60 kg yr, making GERDA the first experiment in the field to reach a half-life sensitivity of 10$^{26}$ yr. We will present the latest results of GERDA in the search for neutrinoless double beta decay.

Speaker: Dr Roman Hiller (UZH)

Slides hiller_TeVPA2018_comp.pdf

289 Latest Results from the CUORE Experiment

The Cryogenic Underground Observatory for Rare Events (CUORE) is the first bolometric experiment searching for neutrinoless double beta decay that has been able to reach the 1-ton scale. The detector consists of an array of 988 TeO2 crystals arranged in a cylindrical compact structure of 19 towers. The construction of the experiment and, in particular, the installation of all towers in the cryostat was completed in August 2016 and data taking started in spring 2017. In this talk we present the neutrinoless double beta decay results of CUORE from examining a total TeO2 exposure of 86.3 kg yr, characterized by an effective energy resolution of 7.7 keV FWHM and a background in the region of interest of 0.014 counts/(keV kg yr). In this physics run, CUORE placed a lower limit on the decay half-life of 130Te > 1.3E25 yr (90% C.L.). We then discuss the improvements in the detector performance achieved in 2018, the new results on the background model and the latest update on the study of rare processes in Tellurium.

Speaker: Dr Giovanni Benato (University of California, Berkeley)

Slides GiovanniBenato_TeVPA_2018.pdf

15:25 Coffee Break

15:25 Coffee Break

15:45 Coffee Break

15:45 Coffee Break

Cosmology: 2

Chair 1-2: Jakob Nordin

Conveners: Mr Jakob Nordin (HU Berlin), Prof. Jens Jasche (Stockholm University), Dr Jesús Zavala Franco (University of Iceland)

290 Fingerprints of the First Stars in the Sky-Average Radio Spectrum

I will present the measurement of an absorption feature in the sky-averaged radio spectrum centered at 78 MHz with the EDGES experiment. The measured feature is broadly consistent with the absorption of photons from the microwave background by neutral hydrogen gas in the intergalactic medium (IGM) due to significant star formation about 180 million years after the Big Bang. Despite this consistency, the amplitude, shape, and frequency of the feature are in tension with physical predictions for either the temperature of the IGM or the microwave background at those redshifts. In my talk I will describe the EDGES measurement, carried out from the desert of Western Australia, and some of the proposed physical implications, if the measurement is independently verified.

Speaker: Dr Raul Monsalve (McGill University)

Slides tevpa.pdf

291 Cosmology with the Zwicky Transient Facility

The Zwicky Transient Facility (ZTF) has started operating earlier this year and is continuously discovering transients throughout the norther sky. Over the course of its three-year survey we expect to find thousands of supernovae, including 2000 type Ia supernovae at low redshifts (z < 0.1) with high-quality lightcurves needed for determining cosmological distances. Such a sample will be essential to anchor the Hubble diagram for upcoming large surveys of higher-redshift supernovae and will allow us to measure anisotropy and structure in the local universe at much better precision. In this talk I will present the predictions for the full three-year ZTF SN Ia survey as well as show its current status.

Speaker: Mr Ulrich Feindt (Stockholm University)

Slides feindt_ztf_cosmo_tevpa_20180830.pdf

292 Searching for ultra light axion-like particles with the CMB

In this talk, I would like to review how the CMB (in particular its temperature and polarization anisotropies) can be used to look for ultra light axion-like particles (ULAs). Such ULAs are numerous in the axiverse scenario and can play many role in cosmology, from Dark Matter to Dark Energy. Moreover, they have been invoked to solve several recent cosmological tensions. In particular, ULAs can potentially be used to solve the tension between the LCDM prediction of H0 extracted from Planck data and that deduced by direct observations of cepheids and SNIa at low-redshift. They have also been suggested as an explanation of the EDGES anomaly — the observation of a puzzling absorption feature in the global 21cm signal. While the standard axion potential leads to ULA behaving like DM when their mass is large enough, a simple generalization of this potential leads to ULAs diluting with arbitrary rate (i.e. they can be chosen to dilute like matter, radiation or at even faster rate). I will explain why such ULAs are phenomenologically very interesting and describe how such generic ULAs can be accurately modeled on cosmological scales thanks to a newly derived fluid approximation that generalizes former work. Finally, I will discuss constraints arising from Planck data on these models, as well as the implications of these constraints for the puzzling cosmological tensions.

Speaker: Dr Vivian Poulin (Johns Hopkins University)

Slides ALP_TeVPA.pdf

293 Inhomogeneous initial conditions and the start of inflation

The robustness of inflation to inhomogeneous initial conditions for matter fields and the spacetime metric is under investigation. If inflationary expansion fails to begin under sufficiently inhomogeneous initial conditions, such that inflation requires fine-tuning of its initial state to occur, then its naturalness is challenged. I will present results for the range of initial conditions which give rise to inflation, based on numerical calculations which evolve the equations of motion of the scale factor and the inflaton field coupled to its quantum fluctuations and metric perturbations through a well-defined set of nonlinear interactions in the Hartree approximation. These results address to what extent inflation can occur under inhomogeneous initial conditions for a few standard slow-roll single-field inflationary models, in calculations which include effects of gravitational back-reaction of perturbations on the background dynamics and on the perturbations themselves, and which have wide applications beyond the inflationary models I will present. Our findings are consistent with recent simulations involving full (3+1) numerical relativity. However, by relying on certain well-studied approximations, our numerical approach can be applied more efficiently to a wide range of models, and can track the evolution of perturbations across a wide range of scales, thereby complementing the recent numerical-relativity simulations.

Speaker: Patrick Fitzpatrick (Center for Theoretical Physics, Massachusetts Institute of Technology)

Slides IDM_talk_4_3.pdf

Dark Matter: 6

Chair 1: Louise Oakes | Chair 2: Nathan Kelley-Hoskins | Chair 3: Klaus Eitel | Chair 4: Dan Hooper | Chair 5: Daniele Gaggero | Chair 6: Michele Doro | Chair 7: Mónica Vázquez-Acosta

Conveners: Louise Oakes (Humboldt Universität zu Berlin), Prof. Marc Schumann (Univertity of Freiburg), Dr Miguel Sánchez-Conde (IFT UAM/CSIC)

294 Testing simple dark matter phase-space prediction methods on cosmological hydro-dynamical simulations of Milky-Way-like galaxies

In the framework of zoom-in cosmological simulations published in Mollitor et al 2015, together with news runs, we compare the phase-space distributions of simulations of Milky Way like Halos with those inferred by the Eddington inversion. This method as presented by Lacroix et al 2018 is able to deduce the phase-space distribution of Dark Matter (DM) at different radii from the mass density distributions of the different components of the target halo i.e. DM, Gas and Stars. We therefore compare the results of the Eddington inversion applied on the different objects, with its velocity distribution in both DM-Only and hydro runs. The comparisons are made within the framework of the spherical formalism and taking into account the velocity anisotropy. For the sake of consistency, we also compare the spherically averaged reconstructed gravitational potential used in the method with the true 3D potential of the simulations. Uncertainties of the method and results are discussed. We aim to assess the validity of the mentioned method as an alternative to the benchmark model used to predict the local DM phase-space properties. Consequences for direct and indirect DM detection are quantified through relevant quantities like moments of the speed distributions and the DM relative velocity. Soon on arxiv.

Speaker: Mr Arturo Nunez-Castineyra (Aix Marseille Université, LAM (Laboratoire d’Astrophysique de Marseille))

Slides NunezCasTeVPa2018.pdf

295 Distinguishing between warm and cold dark matter using gaps in stellar streams

A key prediction of the standard cosmological model -- which relies on the assumption that dark matter is cold, i.e. non-relativistic at the epoch of structure formation -- is the existence of a large number of dark matter substructures on sub-galactic scales. This assumption can be tested by studying the perturbations induced by dark matter substructures on cold stellar streams. Here, we study the prospects for discriminating cold from warm dark matter by generating mock data for upcoming astronomical surveys such as the Large Synoptic Survey Telescope (LSST), and reconstructing the properties of the dark matter particle from the perturbations induced on the stellar density profile of a stream. We discuss the statistical and systematic uncertainties, and show that the method should allow to set stringent constraints on the mass of thermal dark matter relics, and possibly to yield an actual measurement of the dark matter particle mass if it is in the O(1) keV range.

Speaker: Dr Nilanjan Banik (Leiden University/GRAPPA, University of Amsterdam)

Slides streamsppt_TeVPA_Banik.pdf

296 Gravitational waves from spin-1 Dark Matter

I will present a well-motivated dark matter scenario that naturally predicts a strong emission of gravitational waves in the Early Universe. Interplay with Higgs physics as well as the corresponding dark matter phenomenology will be discussed.

Speaker: Dr Camilo Alfredo Garcia Cely (DESY)

Slides TeVPA_GarciaCely.pdf

297 A strong bound on the dark matter fraction in primordial black holes from astronomical data.

The idea that primordial black holes (PBHs) of O(10) solar mass can account for most of the dark matter has been recently reconsidered after the discovery of gravitational waves from binary-black hole merger events. I present a significant update of a robust bound on this scenario based on a conservative modeling of the gas accretion and the subsequent radio and X-ray emission originating by a population of PBHs in our Galaxy. I will address in particular the impact of several key aspects: 1) The dark matter phase-space distribution 2) The accretion physics, by considering realistic numerical simulations that properly capture the radiative feedback mechanism, and model the accretion efficiency as a function of the BH speed. 3) The BH mass distribution, with specific examples (log-normal, power-law distribution) I show that the upper limit on the DM fraction in PBHs is significantly stronger if all these effects are taken into account and a broad mass function is considered. In the last part, I show that our method and formalism can be turned into a window of future detection of a subdominant population of PBHs that amounts to a small fraction of the DM, and present several forecasts focused on forthcoming radio experiments.

Speaker: Dr Daniele Gaggero (SISSA, Trieste)

Slides Gaggero_PBH.pdf

298 Constraints on Dark Matter Annihilation and Decay from CALET Data

Installed on the ISS in August 2015 and taking data since October of that year, CALET (CALorimetric Electron Telescope) is directly measuring the electron+positron cosmic-ray spectrum up into the TeV-region with fine energy resolution and good proton rejection. The latest published total electron+positron spectrum is analyzed for Dark Matter signatures. Limits on annihilation and decay of Dark Matter are calculated by fitting the expected flux from Dark Matter on top of a parametrization of the astrophysical background spectrum to both CALET data and the positron flux measured by AMS-02. Starting from a purely astrophysical scenario with a nearby pulsar as the origin of the positron excess, the spectrum from Dark Matter annihilation or decay, which is numerically calculated with DRAGON, is added, and its scale-factor increased until the fit quality reaches the limit threshold. The flux from Dark Matter is calculated for multiple Dark Matter candidates with varying mass, yielding limits on annihilation cross-section or lifetime as a function of Dark Matter mass for each. In addition to presenting these Dark Matter limits and their comparison with results from other Dark Matter detection methods, possible interpretations of the spectrum measured by CALET including a contribution from Dark Matter will be discussed.

Speaker: Dr Holger Motz (Waseda University)

Slides TeVPA2018Motz.pdf

299 Prospects to find dark matter with cosmic-ray antiprotons and antideuterons

Cosmic rays are one important tool to study dark matter annihilation in our Galaxy. Recently, a possible hint for dark matter annihilation was found in the antiproton spectrum measured by AMS-02. The potential signal is affected by many theoretical and systematic uncertainties making its validation or exclusion a non-trivial task. The most direct but complementary way to test the dark matter interpretation would be the observation of low-energy antinuclei in cosmic rays. We determine the chances to detect antideuterons with GAPS or AMS-02, and the implications on the ongoing AMS-02 antihelium searches. We find that the corresponding antideuteron signal is within GAPS and AMS-02 sensitivity. If, more conservatively, the putative signal is considered as an upper limit on the dark matter annihilation cross section, our results indicate the highest possible fluxes for antideuterons and antihelium compatible with the latest antiproton data.

Speaker: Mr Michael Korsmeier (University of Torino)

Slides Korsmeier_TeVPA.pdf

Gamma Rays: 6

Chair 1: Stefan Ohm | Chair 2: Ruben Lopez-Coto | Chair 3: Sara Buson | Chair 4: Felicia Krauss | Chair 5: Francesco Longo | Chair 6: David Sanchez | Chair 7: Konstancja Satalecka

Conveners: Dr Ruben Lopez-Coto (INFN Padova), Dr Sara Buson (NASA-GSFC), Mr Stefan Ohm (DESY, Zeuthen)

300 Pulsars at the Very High Energies: an update from MAGIC

Pulsars are among the most compact Very High Energy photon sources of the universe, but the physics processes behind their emission are not yet fully understood. MAGIC, a system of two Imaging Atmospheric Cherenkov Telescopes located at 2200 m a.s.l. on the Canary Island of La Palma (Spain), has pioneered the field of VHE pulsar physics and continues contributing to the advancement of our understanding through multiple observation campaigns. By operating in stereoscopic mode, MAGIC can observe gamma rays in energies ranging from a few tens of GeV to several tens of TeV. The recent introduction of a low-energy trigger system, the Sum-Trigger-II, has made MAGIC a unique instrument for the observation of soft sources, including pulsars. In this talk we will review how MAGIC observations contributed to the field of VHE pulsar research. Besides that, we will present details on the Sum-Trigger-II and also results from recent pulsar observations with this system.

Speaker: Mr Giovanni Ceribella (Max-Planck-Institut für Physik)

Slides G. Ceribella -- Pulsars at the Very High Energies: an update from MAGIC.

301 The Energy-dependent $\gamma$-ray Morphology of the Crab Nebula Observed with the $Fermi$ Large Area Telescope

The Crab nebula is a bright emitter of non-thermal radiation across the entire accessible range of wavelengths. The spatial and spectral structures of the synchrotron nebula are well-resolved from radio to hard X-ray emission. The un-pulsed emission at GeV to TeV energies is mostly produced via inverse-Compton scattering of energetic electrons with the synchrotron-emitted photons. The spatial structure observed at these energies provides insights into the distribution of electrons and indirectly constrains the so-far unknown structure of the magnetic field in the nebula. Analyzing the LAT data accumulated over $\sim$9.1 years with a properly refined model for the Crab pulsar's spectrum, we determined the uniform-disk radius of the Crab Nebula to be $0.040^\circ\pm0.002^\circ$ ($2.40'\pm 0.12'$) in the 5--500 GeV band. We report that the systematic uncertainties associated with the PSF are not a serious issue, based on our evaluation of it with the point-like source Mkn 421. By comparison between $Fermi$ LAT and H.E.S.S. results, we find evidence for an energy-dependent shrinking of the Crab Nebula's $\gamma$-ray extension.

Speaker: Mr Paul Kin-Hang YEUNG (University of Hamburg)

Slides TeVPA2018.pdf

302 A new explanation for the two breaks in the spectrum of the Crab Nebula.

The synchrotron spectrum of the Crab Nebula has long been a mystery: rather than having one cooling break, there are at least two breaks: around 1E14 Hz, and around 1E16 Hz. The spectrum cuts off around 1E21 Hz. The break around 1E14 Hz can be explained by synchrotron cooling, but the second break is rather enigmatic and various explanations have been offered, often involving the presence of two distinct electron populations: a flat spectrum resulting in an undetectable spectral cut-off in the UV, and another, steeper spectrum responsible for the X-ray to MeV gamma-ray spectrum, which also must start somewhere in the absorbed UV band. Here we explore another possible origin for the break: we assume that a single power-law electron distribution is injected in the nebula, with an intrinsic cut-off around 1E15 eV. We assume that electron energy losses are initially dominated by adiabatic, rather than synchrotron losses, as long as the flow is faster than 0.5c. If the adiabatic cooling is fast enough and the drop in density large, the initial break at 1E15 eV will be shifted to 1 TeV. We show that if the adiabatic cooling results in electron energies scaling as E~t^(-beta), that the resulting spectral index will be q=1+1/beta, which implies for the Crab nebula beta=0.4 The dominance of adiabatic cooling over synchrotron cooling in the central region of the Crab nebula requires a magnetic field of less than 150 microGauss, consistent with current estimates.

Speaker: Dr Jacco Vink (University of Amsterdam)

Slides jvink_tevpa_2018_v2.pdf

303 The Milky Way in TeV Gamma Rays

In the past 15 years the H.E.S.S. collaboration has intensively surveyed the inner region of our own galaxy, the Milky Way. These observations have culminated in a recent release of 14 publications in a dedicated issue of Astronomy & Astrophysics. In this talk we will present the core part of this programme, the H.E.S.S. Galactic Plane Survey (HGPS), which yielded a catalog of 78 gamma-ray sources. We will discuss this catalog and the source classification. We will also cover the public data products of the HGPS, which have been released to the community. Further highlights of the Galactic science programme of H.E.S.S., like new results of the shell-type supernova remnant RX J1713.7-3946 or the diffuse galactic ridge emission, released together with the HGPS, will also be discussed.

Speaker: David Berge (DESY)

Slides 2018.08.30.TeVPA.HESSGAL.pptx

304 Rise of the Leptons: Pulsar Emission Dominates the TeV Gamma-Ray Sky

Recent HAWC observations have found extended TeV emission coincident with the Geminga and Monogem pulsars. In this talk, I will show that these detections have significant implications for our understanding of the TeV gamma-ray sky. First, the spectrum and intensity of these TeV Halos indicates that a large fraction of the pulsar spindown energy is efficiently converted into electron-positron pairs. This provides observational evidence supporting pulsar interpretations of the rising positron fraction observed by PAMELA and AMS-02. Second, the isotropic nature of this emission provides a new avenue for detecting nearby pulsars with radio beams that are not oriented towards Earth. Lastly, I will show that the total emission from all unresolved pulsars produces the majority of the TeV gamma-ray flux observed from the Milky Way, allowing us to set strong constraints on TeV dark matter models.

Speaker: Dr Tim Linden (The Ohio State University)

Slides tevpa2018.pdf

305 Exploring the nature of a possible neutrino source MGRO J1908+06

MGRO J1908+06 is an unidentified bright TeV source. It has been proposed to be one of the most likely neutrino sources. However, no counterpart of MGRO J1908+06 has been detected at other wavelengths, and its nature remains unknown. PSR J1907+0602 is a 106.6 ms gamma-ray pulsar with high spin down power (∼ 2.8×10^36 erg/s) and is spatially associated with MGRO J1908+06. By analyzing Fermi/LAT and multi-wavelength data, we explore the possibility of MGRO J1908+06 being a PWN powered by PSR J1907+0602.

Speaker: Dr Jian Li (Deutsches Elektronen-Synchrotron (DESY))

Slides PSR_J1907_2018-08-30.pdf

Neutrino Astronomy: 5

Chair 1: Fabrizio Tavecchio | Chair 2: Andrea Palladino | Chair 3: Francesco Villante | Chair 4: Joshua Wood | Chair 5: Summer Blot | Chair 6: Markus Ahlers

Conveners: Dr Aart Heijboer (NIKHEF), Dr Andrea Palladino (DESY), Claudio Kopper (University of Alberta)

306 Neutrino Telescope Baikal-GVD

Baikal-GVD is a next generation, cubic-kilometer scale neutrino telescope which has been constructed since 2015 in the largest and deepest freshwater lake in the world, Lake Baikal. The detector itself is built from independent multi-megaton sub-arrays called clusters whose centers are 300 meters away. Every cluster consists of 8 strings each carrying 36 Optical Modules (OMs) vertically spaced by 15 meters while the uppermost and the undermost layers of OMs are located 750 and 1275 meters below the lake surface, respectively. The strings in the clusters are arranged in heptagons (1 central, 7 peripheral) and the distance between them is 60 meters. The full-scale GVD is going to be an array of ~10.000 OMs with an instrumented volume of about ~2 km3 and it is designed to detect astrophysical neutrino fluxes at energies from a few TeV up to 100 PeV. The first phase (GVD-1) is going to be completed by 2020-2021. The first phase comprises 8 clusters with 2.304 OMs in total and instrumented volume ~ 0.4 km3. The first three clusters of the GVD-1 were successfully installed in 2016, 2017, and 2018, respectively and have been taking data since then. In addition, a new R&D in OMs installation enables to install 2-3 new clusters per year. The most substantial advantages of GVD are very clean water, modularity, easy installation from the frozen surface of the lake and very low content of K40. In this talk we describe the design of Baikal-GVD and present selected results obtained in 2016 – 2017.

Speaker: Lukáš Fajt (IEAP CTU in Prague)

Slides TeVPA_GVD_Fajt.pdf

307 A multi-messenger study of the total galactic high-energy neutrino emission

A detailed multi-messenger study of the high-energy emission from the Galactic plane is possible nowadays thanks to the observations provided by gamma and neutrino telescopes. We show the potential of this approach by using the total gamma flux from the galactic plane measured by HESS at 1TeV and in the longitude range −75° < l < 60°. We compare the HESS observational data with expectations for diffuse gamma emission, calculated by using different assumptions for the CR distribution in the Galaxy. We highlight the existence of an extended region of the galactic plane where the observed flux is substantially larger than the diffuse emission, thus calling for an additional contribution of comparable or larger intensity, possibly due to cumulative emission of resolved and unresolved gamma-ray sources. If this additional contribution is due to hadronic interactions, the considered region also produces a large neutrino flux and should be considered as a preferential target for the search of a galactic component in neutrino telescopes. We estimate the total contribution (i.e. including both diffuse and the source components) of this region to the IceCube HESE neutrino dataset as a function of the spectral index and energy cutoff of the sources, taking also into account the upper limit on galactic neutrino emission provided by Antares.

Speaker: Prof. Francesco Villante (Università dell'Aquila and INFN-LNGS)

Slides villante_TeVPA18.pdf

308 IceCube Search for Galactic Neutrino Sources based on HAWC Observations of the Galactic Plane

We present a search for neutrino emission from Galactic TeV gamma-ray sources detected by the HAWC Observatory. HAWC serves as an excellent instrument to complement IceCube with its energy range extending to very high energies where we expect neutrinos correlated with the gamma-rays observed by HAWC, assuming that the highest energy photons originate from the decay of pions. Using 8 years of IceCube data, we perform two different analyses to test for this possible correlation. The first is a stacked analysis of identified HAWC point sources and the second is a template method which accounts for the full morphology of HAWC sources, including extension.

Speaker: Joshua Wood (University of Wisconsin, Madison)

Slides Joint_IceCube_HAWC_TeVPA_2018.pdf

309 Probing for signs of neutrinos from heavy dark matter decay in the IceCube signal

As the IceCube has steadily collected data over the last several years, certain tensions have emerged between observations on one hand and fits obtained to these observations when assuming a single power-law diffuse astrophysical flux of neutrinos on the other; and between fits obtained using different kinds of datasets (HESE vs through-going muons). We analyse whether these tensions may be mitigated by the addition of a neutrino flux component originating from heavy (i.e. with masses above 100 TeV) dark matter decays possibly in addition to neutrinos from astrophysical sources modeled by an isotropic power-law. To this end, we perform a detailed analysis of the HESE event samples (considering simultaneously the energy, hemisphere and topology of the events) by fitting the mass and lifetime of the dark matter and the normalization and spectral index of an isotropic power-law flux, for various decay channels of dark matter. We find that such a two-component flux is favoured by recent data at IC, and discuss the trends of these fits over the years. We also discuss if the signal at IC could be explained by neutrinos purely from dark matter decays (i.e. without astrophysical neutrinos), in cases where decays proceed via multiple channels.

Speaker: Dr Atri Bhattacharya (University of Liege)

Slides talk0.mini.pdf

310 Atmospheric Neutrinos, GeV to PeV

Atmospheric neutrinos are of interest as a beam for the study of neutrino properties and as a foreground in the search for astrophysical neutrinos. An accurate understanding of their flux is important for both. Uncertainties in the flux of atmospheric neutrinos arise from composition and spectrum of the primary cosmic radiation and from imperfect knowledge of hadronic interactions. Both aspects will be addressed, including constraints from measurements of atmospheric muons.

Speaker: Thomas gaisser (university of delaware)

Slides TeVPA-Gaisser.pdf

311 Measurements of Neutrino Oscillations with IceCube

Although designed to observe neutrinos from astrophysical sources at TeV-PeV energies, IceCube and its DeepCore in-fill array also observe large numbers of atmospheric neutrinos in the 5-50 GeV range, permitting measurements of the “atmospheric” neutrino mixing parameters in a higher energy range complementary to measurements from long-baseline neutrino beam experiments. As these energies are above the tau lepton production threshold, tau neutrino appearance can be observed in addition to muon neutrino disappearance. Recent measurements from two complementary analyses of these effects will be presented.

Speaker: Tyce DeYoung (Michigan State University)

Slides TeVPA_2018.pdf

Gravitational Waves: 2

Chair 1: Daniel Kocevski | Chair 2: Harald Pfeiffer

Conveners: Daniel Kocevski (NASA/MSFC), Dr Harald Pfeiffer (Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute)), Samaya Nissanke (GRAPPA, University of Amsterdam)

312 The next generation of gravitational-wave detectors

The current generation of gravitational-wave detectors have provided a wealth of information from coalescences of binary black holes and binary neutron stars. However, even at design sensitivity these detectors are only able to observe coalescences from the local universe, out to redshifts of a few. In contrast, the next generation of longer and more sensitive gravitational-wave detectors, such as Einstein Telescope and Cosmic Explorer, will detect binary coalescences throughout the entire universe, out to redshifts well beyond 10. Additionally, these next-generation detectors will detect nearby coalescences with exquisite signal-to-noise ratios, enabling precision tests of general relativity and nuclear physics. I will discuss the science goals and technological challenges for this next generation of detectors.

Speaker: Evan Hall (Massachusetts Institute of Technology)

Slides Hall3G.pdf

313 Gravitational Wave Observations of Binary Black Hole Coalescences with LIGO/Virgo

In this talk I will summarize the current astrophysical results from searching for binary black hole mergers in data taken from second generation gravitational wave observatories. I will focus on estimates of binary parameters found with Bayesian inference techniques and state-of-the art waveform models which describe the inspiral, merger and ringdown phases of these coalescences. I will illustrate that highly accurate and fast waveform models are critical for our understanding of these sources and will give an outlook on future challenges. (on behalf of the LIGO and Virgo Scientific Collaborations)

Speaker: Dr Michael Pürrer (Max Planck Institut für Gravitationsphysik, Potsdam)

Slides TeVPA_Talk.pdf

314 TeV gamma-ray observations of GW170817 with H.E.S.S.

In this contribution, the search of high-energy gamma ray emission as electromagnetic counterpart of the binary neutron star merger GW170817 with the H.E.S.S. Imaging Air Cherenkov Telescopes is presented. Observations started 5.3 h after the merger and contained the counterpart SSS17a that was identified several hours later. It stands as the first data obtained by a ground-based pointing instrument on this object. The H.E.S.S. telescopes monitored the source over several days, covering timescales from 0.22 to 5.2 days after the merger and energy ranging between 270 GeV to 8.55 TeV. No significant gamma ray emission has been found. Upper limits on the very-high-energy gamma-ray flux were derived for the remnant of the binary neutron star system, constraining the non-thermal, high-energy emission. We will report on the observation campaign on GW170817 together with the optimised scheduling algorithms that allow H.E.S.S. to react rapidly. We will present the obtain data and discuss constraints to recently proposed models of high-energy, non-thermal longterm emission from GW170817. Finally, an outlook and proposed observation strategies for the next multi-messenger campaigns with H.E.S.S will be provided.

Speaker: Mrs Monica Seglar Arroyo (CEA)

Slides TeVPA_HESS_GW_Seglar.pdf

315 High-energy neutrinos and photons from neutron star mergers

Last year, LIGO-VIRGO collaborations reported detection of the first neutron star merger event, GW170817, which accompanied with observations of electromagnetic counterparts from radio to gamma rays. High-energy gamma rays and neutrinos were not observed. However, the mergers of neutron stars are expected to produce these high-energy particles. In this talk, I will discuss the prospects for coincident detection of these high-energy particles with gravitational waves. Relativistic jets are expected to be launched when the neutron stars merge, which can be a source of high-energy neutrinos. I discuss the neutrino emission from choked jets (Kimura et al. arXiv:1805.1613) and from successful jets including late-time activities (Kimura et al. 2017 ApJL, 848, 4). I also talk about the high-energy photon emissions due to the activity of the central remnant object after the merger event, either a black hole or a neutron star (Murase et al. 2018 ApJL, 854, 60).

Speaker: Dr Shigeo Kimura (Pennsylvania State University)

Slides TeVPA_2018_ssk.pdf

Public Evening Lecture

316 Schwarze Löcher und Neutronensterne: Von Gravitationswellen, Kilonovae und der Entstehung der schweren chemischen Elemente

Speaker: Dr Harald Pfeiffer (Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute))

Friday, 31 August

Cosmology

Chair: Marek Kowalski

317 Neutrino constraints from Cosmology

Follows soon.

Speaker: Martina Gerbino (Stockholm University)

Slides Gerbino_TeVPA2018.pdf

318 Simulations of Structure Formation in SIDM

Self-interacting dark matter provides an interesting alternative dark matter candidate. In my talk I will motivate self-interacting dark matter models from an astrophysical perspective demonstrating their impact on structure formation on galactic scales. I will also discuss first attempts of simulating inelastic models of self-interacting dark matter and show how their impact on structure formation differs from commonly employed elastic models.

Speaker: Mark Vogelsberger (MIT)

Slides talk_vogelsberger.pdf

319 H0 controversy

Follows soon.

Speaker: Mickael Rigault (CNRS)

Slides 1000_Rigault_The_HubbleConstant_Controversy.pdf

10:30 Coffee Break

Highlights

Chair: Markus Ackermann

320 Searches of new physics with >TeV neutrinos in IceCube

The IceCube neutrino observatory has not only discovered the existence of a cosmic neutrino component, but has also made precise measurements of the TeV atmospheric neutrino flux. Using these high-energy atmospheric neutrinos and the astrophysical neutrinos I will present results of searches for new neutrino flavors and interactions. On the former, I will report the status of searches for eV scale sterile neutrinos, whose sensitivity is enhanced in this sample due to resonance induced matter effect. On the latter, I will report the results of search for new neutrino interactions, in particular, between neutrinos and dark matter using the high energy starting events sample.

Speaker: Dr Carlos Argüelles Delgado (Massachusetts Institute of Technology (MIT))

Slides tevpa2018.pdf

321 Latest ISS-CREAM results

Follows soon.

Speaker: Eun-Suk Seo (University of Maryland)

Slides 2018_Seo4TeVPA2.pdf

322 Recent results on the Fermi Bubbles

Follows soon.

Speaker: Karen Yang (University Maryland)

Slides YangTeVPA2018.pdf

323 Learning the physics of CR transport from the gamma-ray sky

The extremely accurate charged cosmic-ray data recently provided by the AMS collaboration and the gamma-ray data from Fermi-LAT and other experiments allowed to enter a new era of precision measurements in the CR field, and offer for the first time the unique opportunity to investigate different transport properties in different regions of the Galaxy. I will review the status of the field, the most relevant anomalies detected so far, possible interpretations and ways to disentangle them. I will focus in particular on a novel energy-dependent characterization of the progressive proton hardening towards the GC region obtained with the skyFACT tool, a gamma-ray analysis tool that combines template fitting and image reconstruction techniques: I will discuss the possible impact of unresolved sources on this trend, and eventually compare different physical interpretations in terms of non-standard properties of CR transport.

Speaker: Dr Daniele Gaggero (GRAPPA, University of Amsterdam)

Slides Gaggero_CRs.pdf

324 EBL review and latest results

The light emitted by all galaxies across the history of the Universe is encoded in the intensity of the extragalactic background light (EBL), the diffuse cosmic radiation field at ultraviolet, optical, and infrared wavelengths. The EBL is a source of opacity for high-energy γ rays via the photon-photon interaction (γγ → e+e−), leaving a characteristic attenuation imprint in the spectra of distant γ-ray sources. In this talk, I will report on an unprecedented measurement of the EBL using data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope, which has allowed us to measure the star-formation history and the number density of faint galaxies during the re-ionization epoch.

Speaker: Dr Marco Ajello (Clemson University)

Slides EBL_TeVPA2018.pdf EBL_TeVPA2018.pptx

Wrap-up

Chair: Markus Ackermann

325 Wrap-up

Speakers: Gianfranco Bertone, Markus Ackermann

12:40 Lunch Break

Dark Matter: 7

Chair 1: Louise Oakes | Chair 2: Nathan Kelley-Hoskins | Chair 3: Klaus Eitel | Chair 4: Dan Hooper | Chair 5: Daniele Gaggero | Chair 6: Michele Doro | Chair 7: Mónica Vázquez-Acosta

Conveners: Louise Oakes (Humboldt Universität zu Berlin), Prof. Marc Schumann (Univertity of Freiburg), Dr Miguel Sánchez-Conde (IFT UAM/CSIC)

326 Dark Matter search with the Fermi Large Area Telescope

Observations of high-energy gamma rays are one of the most promising tools to constrain or reveal the nature of dark matter. During the remarkable ten years of the Fermi satellite mission, the data from its Large Area Telescope (LAT) were used to set constraints on the dark matter cross section to various particle channels which cut well into the theoretically motivated region of the parameter space, challenging the WIMP dark matter paradigm, for dark matter masses in the 1-100 GeV range. In this talk, I will review the latest results of the dark matter searches with the LAT and will comment on the strategies for the near future.

Speaker: Gabrijela Zaharijas (Center for astrophysics and cosmology/Un. of Nova Gorica)

Slides Zaharijas_TeVPA18_LAT_v3.pdf

327 Evidence Against a Dark Matter Explanation of the Galactic Center Excess

An anomalous, apparently diffuse, gamma-ray signal not readily attributable to known Galactic sources has been found in Fermi space telescope data covering the central ~10 degrees of the Galaxy. This "Galactic Center Gamma-Ray Excess" (GCE) signal has a spectral peak at ~2 GeV and reaches its maximum intensity at the Galactic Centre (GC) from where it falls off as a radial power law ~r^{-2.4}. Given its morphological and spectral characteristics, the GCE is ascribable to self-annihilation of dark matter particles governed by an Navarro-Frenk-White-like density profile. However, it could also be composed of many dim, unresolved point sources for which millisecond pulsars (MSPs) or pulsars would be natural candidates given their GeV-peaked spectra. Statistical evidence that many sub-threshold point sources contribute up to 100% of the GCE signal has recently been claimed. We have developed a novel analysis that exploits hydrodynamical modelling to better register the position of gamma-ray emitting gas in the Inner Galaxy. Our improved analysis reveals that the excess gamma-rays are spatially correlated with stellar structures of the Galactic Bulge and Centre. Given these correlations, we argue that the excess is not a dark matter phenomenon but rather associated with very old stars in the Inner Galaxy

Speaker: Roland Crocker (Australian National University)

Slides TeVPA_2018_Berlin_Crocker.pdf

328 Studying Dark Matter properties with the CMB

In this talk, I would like to review how the CMB (in particular its temperature and polarization anisotropies) can be used to perform both direct and indirect detection of DM. Firstly, I will show the great complementarity between underground direct detection experiment and the CMB in looking for direct scattering between dark and baryonic matter. I will then discuss how the CMB challenges the dark matter explanation of the EDGES anomaly — the observation of a puzzling absorption feature in the global 21cm signal. Secondly, I will show how the CMB can be used to put stringent constraints on DM models leading to energy injection, e.g DM annihilations, decay, PBH evaporation and accretion. I will compare CMB bounds to those coming from galactic cosmic and gamma ray searches and illustrate how the 21cm signal, a major target of next generation surveys, can be used to significantly improve over current limits.

Speaker: Dr Vivian Poulin (Johns Hopkins University)

Slides DMcosmo_TeVPA.pdf

329 The Status of Interpretations of the Galactic Center Excess

I will review the arguments in favor of either pulsars or annihilating dark matter as the source of the GeV excess observed from the Inner Galaxy. While it is not clear at this time which of these interpretations is correct, I will argue that upcoming observations will likely clarify the situation considerably.

Speaker: Prof. Dan Hooper (Fermilab/University of Chicago)

Slides TeVPA-2018_Hooper.pdf

330 The low-energy excess at ANTARES and IceCube Neutrino Telescopes: a potential Dark Matter signature

Recent analyses of the diffuse TeV-PeV neutrino flux highlight a tension between different IceCube data samples that strongly suggests a two-component scenario rather than a single steep power-law. In this talk, I show how such a tension is further strengthened once the latest ANTARES (9-year) and IceCube (6-year) data are combined together. Remarkably, both experiments show an excess in the same energy range (40-200 TeV), whose origin could intriguingly be related to a Dark Matter signature. Hence, I discuss in a multi-messenger context the Dark Matter features required to account for the low-energy excess according to a statistical analysis on the neutrino energy spectrum and on the angular distribution of neutrino events.

Speaker: Dr Marco Chianese (University of Southampton)

Slides TeVPA18_Chianese.pdf

331 p-wave annihilating dark matter and the EDGES 21-cm signal

I will demonstrate how current and future measurements of the global 21-cm signal could provide new constraints on models of p-wave annihilating dark matter (DM), over a broad range of DM masses. 21-cm observations are sensitive to the baryon temperature at the end of the cosmic dark ages, and are particularly well-suited to constrain p-wave models, because the energy injection rate from p-wave annihilation increases dramatically around this time due to the formation of large gravitationally bound structures. In addition to the standard cold DM structure formation scenario, we analyze the scenario in which a component of DM obtains a nonzero temperature through its interactions with visible matter. This analysis enables us to set constraints on milli-charged scalar DM, which has been proposed as a possible explanation for the claimed 21-cm signal from the EDGES experiment, and more generally to explore the possible relationship between p-wave annihilating DM and the deep EDGES absorption trough.

Speaker: Gregory Ridgway (MIT)

Slides TeVPA2018.pdf

Galactic Science: 3

Chair: Jacco Vink

Conveners: Mr Dmitry Khangulyan (Rikkyo University), Emma de Ona Wilhelmi (CSIC-IEEC), Dr Luigi Tibaldo (IRAP)

332 Bubbling balls of leptons: review on MHD simulations of PWNe

PWN make up the majority of the identified galactic TeV sources and are a key ingredient to understand the high energy sky. In this contribution, I will review recent progress in magnetohydrodynamic and particle transport modeling of PWN, highlighting advances with fully three-dimensional global models. It is now clear that the MHD kink- and Kelvin Helmholtz-type instabilities lead to turbulent flows in the nebula with direct impact on dynamics and morphology. Close to the termination shock, the telltale jet and torus structure is still well recovered by the simulations, with varying strengths of the two features depending on the pulsar obliqueness. Emergence of current sheets and magnetic dissipation govern the turbulent nebula proper. The high velocity fluctuations give rise to efficient eddy-diffusive transport of particles, indicating that both advection and diffusion play an important role in particle transport. TeV emission due to inverse Compton upscattering from the nebula leptons has so far only been incorporated in 2D simulations. I will comment on the status of high energy modeling and conclude with a discussion of solved and unsolved problems posed by PWNe.

Speaker: Dr Oliver Porth (ITP Frankfurt)

333 Review of binary systems seen in gamma rays

I will review the current state of the art in available data and emission models of binary systems at high- (0.1-100GeV) and very-high-energy (>100GeV) gamma rays. The majority among these systems consists of an early type star with a strong stellar wind and a compact companion. Commonly accepted models assume that the compact object is a pulsar having a pulsar wind driven by the pulsar's spin-down power. An alternative scenario is Microquasar model, where a collimated relativistic jet associated with the compact object is observed and suspected to be connected to the detected high-energy emission. A closer look to the known binary systems reveals distinctive aspects regarding orbital parameters and/ or the nature of binary constituents. I will discuss the long-sought question whether or not gamma-ray binaries can be understood in terms of variations from an underlying, generalized scheme reviewing the sources known up to now. Furthermore, I will give an outlook what future instruments can do to advance the field.

Speaker: Daniela Hadasch (ICE)

Slides binaries_TeVPA2018_Hadasch_final.pdf

334 Detection of the TeV Gamma-Ray Binary PSR J2032+4127/ MT91 213

PSR J2032+4127 is a young gamma-ray pulsar located in the same direction as the extended TeV gamma-ray source TeV J2032+4130. The pulsar has recently been discovered to be in a 45-50 year period, highly eccentric binary orbit with the Be star MT91 213. Periastron occurred in November 2017 and over this period an intense observational campaign was conducted by the TeV gamma-ray telescope arrays VERITAS and MAGIC, and the Swift X-ray telescope. These observations detected a significant enhancement in the X-ray and TeV gamma-ray flux, with the emission reaching an order of magnitude higher than the historical level. I will present results of these campaigns, compare this system with other TeV gamma-ray binaries and explore the relationship between this system and TeV J2032+4130.

Speaker: Dr Ralph Bird (UCLA)

Slides TeVPA.pdf

335 TeV Gamma-Ray Spectral and Morphological Studies of 2HWC J2019+367

The High Altitude Water Cherenkov (HAWC) gamma-ray observatory has been fully operational since March 2015 in central Mexico. Using $\sim$3 years of HAWC data and recently developed energy estimation techniques, now it is possible to study the highest energy sources with their energy-dependent morphology. The unidentified VER J2019+368 is among the highest energy sources and shows significant emission above 56 TeV reconstructed energy. In the previous works, it has been associated with the PSR J2021+3651 and its X-ray pulsar wind nebula. But still, the nature of VER J2019+368 remains unsettled, owing to its extended complex gamma-ray emission region. In this work, we investigate the energy dependency of the morphology and the spectrum of VER J2019+368 up to the highest gamma-ray energies. With these results, we explore the different scenarios of leptonic and/or hadronic origin to account for the observed gamma-ray emission. Most likely leptonic origin allows us to investigate the expected gamma-ray pulsar wind nebula properties of the system.

Speaker: Mr Vikas Joshi (Max-Planck-Institut für Kernphysik)

Slides Vikas_Joshi_TeVPA_2018_VERJ2019.pdf

336 Observations of SNR G24.7+0.6 with the MAGIC Telescopes

SNR G24.7+0.6 is a 9.5 kyrs radio and GeV gamma-ray supernova remnant (SNR) evolving in a dense medium. In the GeV regime, SNR G24.7+0.5 shows a hard spectral index which which if extended to very high energies should be easily detected by current Cherenkov telescopes. We observed the field of view of SNR G24.7+0.6 with the MAGIC telescopes. The region shows a complex environment, displaying different structures in the TeV regime. Applying morphological and spectral analysis techniques, we distinguished three different regions of very-high energy gamma-rays. The results will be discussed in the context of origin of these gamma-ray accelerators.

Speaker: Emma de Ona Wilhelmi (CSIC-IEEC)

Slides SNRG24_TEVPA2018_EOW.pdf

Gamma Rays: 7

Chair 1: Stefan Ohm | Chair 2: Ruben Lopez-Coto | Chair 3: Sara Buson | Chair 4: Felicia Krauss | Chair 5: Francesco Longo | Chair 6: David Sanchez | Chair 7: Konstancja Satalecka

Conveners: Dr Ruben Lopez-Coto (INFN Padova), Dr Sara Buson (NASA-GSFC), Mr Stefan Ohm (DESY, Zeuthen)

337 AGILE gamma-ray transients and IceCube neutrinos

We present the results of a systematic search in the AGILE quick-look database for transient gamma-ray sources above 100 MeV that are temporally and spatially coincident with published high-energy neutrino IceCube events. AGILE is a small scientific mission of the Italian Space Agency (ASI) in cooperation with INAF, INFN, CIFS, and with the participation of several Italian companies and Universities. The satellite, in orbit since April 23th, 2007, is devoted to gamma-ray astrophysics from a few tens of MeV to a few tens of GeV.

Speaker: Ms Carlotta Pittori (INAF-OAR and ASI-SSDC)

Slides AGILE-Neutrinos_TeVPA_2018_pittori.pptx

338 Gamma-ray counterparts of IceCube track-type high-energy neutrino events

Observations performed by the Large Area Telescope (LAT) on board of the Fermi Gamma-ray Space Telescope around the IC170922A region revealed a flaring gamma-ray blazar, TXS 0506+056, in spatial and temporal coincidence with the neutrino event detected by the IceCube Neutrino Observatory. Archival searches of other historical, well-reconstructed high-energy neutrino events have revealed further potential gamma-ray counterparts less bright than TXS 0506+056 during the 2017 flare. The electromagnetic properties are crucial input to any kind of modeling proving the source as neutrino counterpart candidate. A detailed study will be presented, using 9.6 years of Fermi-LAT data in the 100 MeV - 1 TeV energy range, that focuses on a selection of sky regions of historical neutrino events detected by IceCube.

Speaker: Simone Garrappa (DESY)

Slides SGarrappa_TeVPA2018_310818.pdf

339 Towards more robust models of extragalactic gamma-ray propagation

Emission of distant (redshift z>0.1) extragalactic sources in the GeV-TeV energy range may be significantly transformed during the propagation between the source and the observer. So far, the only robust result in this area was the firm establishment of the existence of the \gamma\gamma\rightarrow e^{+}e^{-} pair production process. During the last 8 years, there were many other claims that were ultimately rejected or remain unconfirmed. Namely, 1) the strength and structure of the extragalactic magnetic field (EGMF) is still virtually unknown, 2) the anomalies indicating the presence of \gamma\rightarrow axion-like particle (ALP) oscillation in magnetic fields are still not confirmed 3) for some sources such as extreme TeV blazars, the shape of the primary spectrum is still not well constrained. We argue that many difficulties in this area of research have a methodical origin. We illustrate these difficulties in the framework of intergalactic cascade models that include secondary (cascade) gamma-rays produced in electromagnetic (EM) cascades initiated by primary gamma-rays or protons. For instance, we argue that the recent claim of astro-ph/1804.08035 that the EGMF strength is constrained to be above 0.3 pG for the case of stable sources is driven mainly by the assumptions made by the authors (namely, that “accounting for the cascade contribution does not change the best-fit spectrum of the central point source in the entire Fermi-LAT energy band by more than 5 \sigma”). As well, recent works aimed at the discovery of the \gamma\rightarrow ALP process, besides other methodical difficulties, do not consider a possible source of background from intergalactic electromagnetic cascades. We apply intergalactic cascade models to the case of extreme TeV blazar observations with atmospheric Cherenkov telescopes (ACTs) and the Fermi-LAT telescope. We show that the development of intergalactic EM cascades may, in principle, represent a dangerous source of astrophysical background for \gamma\rightarrow ALP searches. On the other hand, intergalactic EM cascades from primary protons and nuclei do not modify the effective opacity of the Universe significantly. We discuss how to falsify these “electromagnetic” and “hadronic” intergalactic cascade models with contemporary and future gamma-ray observations, thus allowing to suppress the background for the \gamma \rightarrow ALP process searches with ACTs and Fermi LAT. We also argue that while measuring weak EGMF (~1 fG or less on the spatial scale of 1 Mpc) with weakly variable sources, ACTs such as the Cherenkov Telescope Array (CTA) should be supplemented by space-based telescopes such as Fermi LAT. We argue that these results are robust with respect to many systematic effects. Some details of our calculation methods are available in [T.A. Dzhatdoev et al., A&A, 603, A59 (2017)].

Speaker: Timur Dzhatdoev (SINP MSU)

Slides TeVPA-Cascades.pdf

340 In-vacuo-dispersion-like spectral lags in gamma-ray bursts

Some recent studies exposed rather strong statistical evidence of in-vacuo-dispersion-like spectral lags for gamma-ray bursts (GRBs), a linear correlation between time of observation and energy of GRB particles. Those results focused on testing in-vacuo dispersion for the most energetic GRB particles, and in particular only included photons with energy at emission greater than 40 GeV. We here extend the window of the statistical analysis down to 5 GeV and find results that are consistent with what had been previously noticed at higher energies.

Speaker: Mr Michele Ronco (Sapienza University of Rome, INFN, University of Valencia, IFIC)

Slides TeVPA18_Ronco.pdf

341 Modelling of gamma ray bursts and predictions for CTA observations

We use a time-dependent numerical model to calculate the prompt GRB emission (spectra and light curves) in GeV/TeV energy range. The emission is modelled by combining a time-dependent radiative code, solving for the electron and photon distributions, with a dynamical code calculating the evolution of the physical conditions in the shocked regions of the outflow. The microphysics parameters and the parameters defining the dynamical evolution are constrained by the observed spectral evolution in the standard sub-MeV energy range as well as by Fermi/LAT observations. The confrontation of our results with the simulated GRB population led to further constraints of the parameter space for GRB prompt emission. The analysis of simulated spectra and lightcurves was performed using the Gammapy package. The results of our study will be used in the estimate of the GRB detection rate and the optimisation of the observations with CTA.

Speaker: Zeljka Bosnjak (FER-University of Zagreb)

Slides bosnjak_tevpa_2.pdf

342 The TAIGA Experiment

The Tunka Advanced Instrument for cosmic ray and Gamma ray Astrophysics, TAIGA, aims at accessing the gamma-ray sky in the multi-TeV to PeV energy regime. This energy range is key to spectroscopically resolving the cutoff regime of the - yet to be identified - Galactic cosmic ray Pevatrons. Sensitive gamma-ray observations in this energy range are essential for this task, and require a very large instrumented area (several square kilometers). TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma ray Astronomy) experiment covers this energy range using a combination of different complementing detection techniques: Widely spaced large-angle imaging air Cherenkov telescopes (IACTs), a Cherenkov light shower front sampling timing array, and muon particle detectors. IACT images are combined with time- and amplitude-information from the timing array using a novel hybrid reconstruction method. This approach allows to maximize the effective area and to reach at the same time a good gamma-hadron separation also at low energies (few TeV). The muon detectors improve the gamma-hadron separation at higher energies. Here, the TAIGA design, the hybrid reconstruction principles, and the status of TAIGA will be presented.

Speaker: Martin Tluczykont (University of Hamburg)

Slides Berlin_TeVPA_2018_Tluczykont.pdf

343 Status of the LHAASO observatory

LHAASO is a complex of air shower detector arrays under construction. With the detection of muons in air shower, the arrays have strong selection power of VEH-UHE gamma rays out of the CR background. Its wide FoV and continuous operation time will provide a survey sensitivity of 10 mini-Crab-unit over the whole northern sky and monitoring for transient phenomena, such as GRB HE-photons. The differential sensitivity better than 0.1 CU covers the wide energy range up to 100 TeV. This opens an opportunity of finding concrete evidences for galactic CR sources. The first 1/4 of the array will be put in operation in the beginning of next year. The status of the construction will be updated in the report.

Speaker: Zhen Cao (Institute of High Energy Physics)

Slides TEVPA-2018-ZC.pdf

Neutrino + Cosmic Rays: 6

Chair: Markus Ahlers

Conveners: Dr Aart Heijboer (NIKHEF), Dr Andrea Palladino (DESY), Andrei Bykov (Ioffe Physico-Technical Institute), Claudio Kopper (University of Alberta), Dr Sabrina Casanova (IFJ PAN &amp; MPIK HD), Dr denise boncioli (DESY)

344 Multi-messenger studies at ultra-high energies with the Pierre Auger Observatory

The Pierre Auger Observatory is the world’s largest cosmic-ray detector, sensitive to cosmic rays with energy exceeding $\sim 10^{17}$ eV. In addition to charged cosmic rays that form the bulk of the cosmic-ray flux at ultra-high energies, Auger is sensitive to ultra-high energy neutral messengers (photons, neutrinos, and neutrons). The latter are particularly exciting as they are expected to arrive in spatial, and temporal coincidence with electromagnetic counterparts from the yet unknown sources of ultra-high energy cosmic rays, and can be used for triggering, or follow-up in multi-messenger transient searches. I will review the activities of Auger in a multi-messenger context, with focus on the searches for neutral particles in coincidence with gravitational wave events, multi-messenger cross-correlation searches, and realtime coincidence searches within the Astrophysical Multi-messenger Observatory Network (AMON).

Speaker: Dr Foteini Oikonomou (European Southern Observatory)

Slides TeVPA2018_Oikonomou.pdf

345 Search for correlations of ultra-high-energy cosmic rays and high-energy neutrinos

Cosmic rays were discovered a century ago, however the sources of the ultra-high-energy events remain unidentified. It is believed that the same environments that accelerate ultra-high-energy cosmic rays (UHECRs) also produce high-energy neutrinos via hadronic interactions. Two out of three joint analyses of the IceCube Neutrino Observatory, the Pierre Auger Observatory and the Telescope Array yielded hints for a possible directional correlation of high-energy neutrinos and UHECRs. The first analysis is based on counting pairs of neutrinos and UHECRs, while the second analysis uses neutrino directions for a stacking approach. The third analysis was based on using UHECR event regions as spatially extended signal templates. The next step is to include neutrino data measured by ANTARES in order to increase sensitivity to possible correlations in the Southern Hemisphere. Additionally, an improved analysis with an approach complementary to the other analyses has been developed. This analysis searches for neutrino point sources in windows around UHECRs with window extensions estimated from deflections by galactic magnetic fields. We present this new analysis for searching common hadronic sources as well as recent results of all correlation analyses with updated data from all contributing experiments.

Speaker: Lisa Schumacher (RWTH Aachen)

Slides 20180831_lschumacher_tevpa_uhecr-nu-correlation.pdf

346 Using cosmogenic neutrinos to determine the fraction of protons in ultra-high-energy cosmic rays

When ultra-high-energy cosmic rays (UHECRs) travel through the universe they create cosmogenic neutrinos via several interactions. The expected flux at Earth of these cosmogenic neutrinos generally depends on multiple parameters describing the sources and propagation of UHECRs. However, at a neutrino energy of ~1 EeV a 'sweet spot' occurs where this flux only depends strongly on two parameters, the source evolution and the fraction of protons in UHECRs. Current neutrino experiments are already constraining these parameters, showing that the sources of UHECRs cannot have a large proton fraction and strong source evolution. Upcoming neutrino experiments will be able to further constrain the fraction of protons in UHECRs even for a negative source evolution.

Speaker: Dr Arjen van Vliet (DESY Zeuthen)

Slides 20180831_AvanVliet_ProtonFraction.pdf

347 Cosmogenic neutrinos from a combined fit of the Auger spectrum and composition

We present a combined fit of the Auger spectrum and composition based on a newly developed code for the extragalactic propagation of cosmic ray nuclei (PriNCe). This very efficient numerical solver of the transport equations allows for scans over large ranges of unknown UHECR source parameters. Here, we present a study of a generalized source population with three parameters (rigidity-dependent maximal energy, spectral index and redshift evolution). By scanning over the redshift source evolution we derive a robust estimate of the allowed range of the cosmogenic neutrino flux. We also test the robustness under alternative assumptions for the source model.

Speaker: Mr Jonas Heinze (Desy Zeuthen)

Slides 2018_08_31_TeVPA.pdf 2018_08_31_TeVPA.pptx

348 Connecting UHECR theory to data: the benefits of Bayesian hierarchical models

The study of UHECR is challenged by both the rarity of events and the difficulty in modelling their production, propagation and detection. The physics behind these processes is complicated, requiring high-dimensional models which are impossible to fit to data using traditional methods. Whilst non-trivial, it is indeed possible to directly fit realistic, physical models to the UHECR data. The combination of Bayesian hierarchical modelling with the advanced computational methods available allows us to fit complex models with a large number of parameters whilst naturally connecting to the underlying physics. The main benefits are that all aspects of the data (energy, composition and arrival direction) can be used simultaneously and that uncertainties are modelled consistently, resulting in an approach that can constrain UHECR models in a way that is both physically and statistically principled. A framework for such an analysis is presented, along with results from the fit of a phenomenological model to data from the Pierre Auger Observatory. The potential to extend this method to more realistic physical models and multi-messenger observations is also discussed.

Speaker: Ms Francesca Capel (KTH Royal Institute of Technology)

Slides UHECR_theory_to_data_FC.pdf

349 Ultrahigh energy cosmic rays from neutron-star mergers

In the context of the recent multi-messenger observation of neutron-star merger GW170817, we examine whether such objects could be sources of ultrahigh energy cosmic rays. At first order, the energetics and the population number is promising to envisage the production of a copious amount of particles, during the first minutes to weeks from the merger. On the other hand, the strong radiative environment in the kilonova ejecta can be an important background causing energy losses for cosmic-ray nuclei but also the emission of associated high-energy neutrino signatures. We model the evolution of the photon density in the kilonova ejecta and calculate numerically its impact on ultrahigh energy astroparticle spectra.

Speaker: Mr Valentin Decoene (Institut d'Astrophysique de Paris)

Slides VDecoene_TeVPA_2018.pdf

350 High energy neutrino emission from obscured sources through the pp channel

The existence of an astrophysical neutrino flux at TeV to PeV energies has now been firmly established by the IceCube collaboration. However, the sources responsible for this flux have not yet been identified. The most important candidates, steady emitting blazars and transient gamma-ray bursts, favoured on the basis of their high gamma-ray luminosity, are now ruled out as the dominant source populations. Therefore, it is necessary to investigate alternative source classes. The observed neutrino flux is at the level expected from its presumed connection to ultra-high-energy cosmic rays, implying high interaction efficiencies of the parent cosmic rays in the sources. When assuming sources transparent to gamma-rays, this leads to a tension with the intergalactic gamma-ray background observed by Fermi. This severely constrains the possibility that the neutrino flux originates in cosmic ray reservoirs where pp-interactions are efficient, but gamma-rays can escape unhindered. We investigate the possibility that the astrophysical neutrino flux originates in sources which are obscured by dense columns of gas, which can attenuate the gamma-ray flux. This scenario is applied to ultra-luminous infrared galaxies, which are among the most powerful sources in our universe, common at high redshift, and feature high gas densities. We show such a source class can contribute to the observed neutrino flux.

Speaker: Matthias Vereecken (Vrije Universiteit Brussel)

Slides TeVPA.pdf

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