Conveners
Gamma Rays: 1
- Sara Buson (NASA-GSFC)
- Ruben Lopez-Coto (INFN Padova)
- Stefan Ohm (DESY, Zeuthen)
Gamma Rays: 2
- Ruben Lopez-Coto (INFN Padova)
- Sara Buson (NASA-GSFC)
- Stefan Ohm (DESY, Zeuthen)
Gamma Rays: 3
- Ruben Lopez-Coto (INFN Padova)
- Sara Buson (NASA-GSFC)
- Stefan Ohm (DESY, Zeuthen)
Gamma Rays: 4
- Sara Buson (NASA-GSFC)
- Ruben Lopez-Coto (INFN Padova)
- Stefan Ohm (DESY, Zeuthen)
Gamma Rays: 5
- Sara Buson (NASA-GSFC)
- Ruben Lopez-Coto (INFN Padova)
- Stefan Ohm (DESY, Zeuthen)
Gamma Rays: 6
- Stefan Ohm (DESY, Zeuthen)
- Ruben Lopez-Coto (INFN Padova)
- Sara Buson (NASA-GSFC)
Gamma Rays: 7
- Stefan Ohm (DESY, Zeuthen)
- Sara Buson (NASA-GSFC)
- Ruben Lopez-Coto (INFN Padova)
Description
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
Riccardo Rando
(University of Padova and INFN)
27/08/2018, 16:15
Gamma-rays
Talk
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...
Mr
Hiroki Yoneda
(University of Tokyo)
27/08/2018, 16:35
Gamma-rays
Talk
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...
Dr
Andrey Timokhin
(NASA/GSFC)
27/08/2018, 16:50
Gamma-rays
Talk
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...
Mr
Cosimo Nigro
(DESY Zeuthen)
27/08/2018, 17:05
Gamma-rays
Talk
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...
Dr
Henrike Fleischhack
(Michigan Tech)
27/08/2018, 17:20
Gamma-rays
Talk
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...
Dr
Fabian Schussler
(CEA-Saclay)
27/08/2018, 17:35
Gamma-rays
Talk
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...
Francesco Longo
28/08/2018, 14:00
Gamma-rays
Talk
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...
Dr
Ng Kenny Chun Yu
(Weizmann Institute of Science)
28/08/2018, 14:20
Gamma-rays
Talk
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...
Eva Leser
(Universität Potsdam/ DESY, D-15738 Zeuthen, Germany)
28/08/2018, 14:35
Gamma-rays
Talk
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...
Mr
Matteo Balbo
(ISDC, Univeristé de Genève)
28/08/2018, 14:50
Gamma-rays
Talk
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...
Dr
Klaus Reitberger
(Zentrum für Astronomie,Universität Heidelberg AND Institut für Astro- und Teilchenphysik, Universität Innsbruck)
28/08/2018, 15:05
Galactic
Talk
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...
Mr
Chang Dong Rho
(University of Rochester)
28/08/2018, 15:20
Gamma-rays
Talk
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...
Dr
Ruizhi Yang
(Max-Planck-Institut für Kernphysik)
28/08/2018, 16:45
Gamma-rays
Talk
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...
Mr
Chad Brisbois
(Michigan Technological University)
28/08/2018, 17:05
Gamma-rays
Talk
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...
Dr
Troy Porter
(Stanford University)
28/08/2018, 17:20
Gamma-rays
Talk
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...
Dr
Maria Victoria del Valle
(Potsdam University)
28/08/2018, 17:35
Gamma-rays
Talk
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...
Ms
Maria Haupt
(DESY)
28/08/2018, 17:50
Gamma-rays
Talk
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...
Tova Yoast-Hull
(Canadian Institute for Theoretical Astrophysics)
28/08/2018, 18:05
Gamma-rays
Talk
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...
Mr
Giacomo Principe
(ECAP - Erlangen Nurenberg University)
29/08/2018, 14:00
Gamma-rays
Talk
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...
Dr
Sara Cutini
(INFN Perugia)
29/08/2018, 14:15
Gamma-rays
Talk
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...
David Paneque
(Max Planck Institute for Physics)
29/08/2018, 14:30
Gamma-rays
Talk
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...
Luca Foffano
(University of Padova, INFN)
29/08/2018, 14:45
Gamma-rays
Talk
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...
Dr
Alicja Wierzcholska
(Institute of Nuclear Physics PAS)
29/08/2018, 15:00
Gamma-rays
Talk
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...
Dr
Jagdish Joshi
(University of Johannesburg)
29/08/2018, 15:15
Gamma-rays
Talk
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...
Dr
Sergei Vafin
(Institute for Physics and Astronomy, University of Potsdam, D-14476 Potsdam, Germany)
29/08/2018, 15:30
Gamma-rays
Talk
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...
Dr
ANNE LEMIERE
(APC)
29/08/2018, 16:15
Gamma-rays
Talk
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...
Ms
Claire Guépin
(Institut d'Astrophysique de Paris)
29/08/2018, 16:35
Gamma-rays
Talk
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...
Emma Storm
(University of Amsterdam)
29/08/2018, 16:50
Gamma-rays
Talk
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...
Dr
Dmitry Malyshev
(Erlangen Center for Astroparticle Physics)
29/08/2018, 17:05
Gamma-rays
Talk
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...
Ms
Lili Yang
(University of Nova Gorica), Prof.
Soebur Razzaque
(University of Johannesburg)
29/08/2018, 17:20
Gamma-rays
Talk
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...
Mr
Thomas Edwards
(GRAPPA, University of Amsterdam)
29/08/2018, 17:35
Gamma-rays
Talk
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...
Michael Kachelriess
(NTNU)
29/08/2018, 17:50
Gamma-rays
Talk
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...
Mr
Giovanni Ceribella
(Max-Planck-Institut für Physik)
30/08/2018, 16:15
Gamma-rays
Talk
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...
Mr
Paul Kin-Hang YEUNG
(University of Hamburg)
30/08/2018, 16:32
Gamma-rays
Talk
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...
Dr
Jacco Vink
(University of Amsterdam)
30/08/2018, 16:49
Gamma-rays
Talk
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...
David Berge
(DESY)
30/08/2018, 17:06
Gamma-rays
Talk
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...
Dr
Tim Linden
(The Ohio State University)
30/08/2018, 17:23
Gamma-rays
Talk
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...
Dr
Jian Li
(Deutsches Elektronen-Synchrotron (DESY))
30/08/2018, 17:40
Gamma-rays
Talk
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...
Ms
Carlotta Pittori
(INAF-OAR and ASI-SSDC)
31/08/2018, 14:00
Gamma-rays
Talk
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...
Simone Garrappa
(DESY)
31/08/2018, 14:17
Gamma-rays
Talk
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...
Timur Dzhatdoev
(SINP MSU)
31/08/2018, 14:34
Gamma-rays
Talk
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...
Mr
Michele Ronco
(Sapienza University of Rome, INFN, University of Valencia, IFIC)
31/08/2018, 14:51
Gamma-rays
Talk
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...
Zeljka Bosnjak
(FER-University of Zagreb)
31/08/2018, 15:08
Gamma-rays
Talk
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...
Martin Tluczykont
(University of Hamburg)
31/08/2018, 15:25
Gamma-rays
Talk
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...
Zhen Cao
(Institute of High Energy Physics)
31/08/2018, 15:42
Gamma-rays
Talk
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...