Conveners
Cosmology and Astroparticles session on Zoom and in Main Auditorium
- Julia Harz
- Camilo Garcia Cely
Cosmology and Astroparticles session on Zoom and in Main Auditorium
- Julia Harz
- Camilo Garcia Cely
Mr
Paul Frederik Depta
(DESY)
22/09/2020, 14:15
Cosmology & Astroparticle Physics
Dark matter (DM) as a thermal relic of the primordial plasma is increasingly pressured by direct and indirect searches, while the same production mechanism in a decoupled sector is much less constrained. We extend the standard treatment of the freeze-out process to such scenarios and perform precision calculations of the annihilation cross section required to match the observed DM abundance....
Oindrila Ghosh
(II. Institute for Theoretical Physics, University of Hamburg)
22/09/2020, 14:28
Cosmology & Astroparticle Physics
I will describe a new scheme for the detection of radio signals from the decay of axions and axion-like particles, called *axion gegenschein*, using next-generation facilities such as SKA. Ambient radiation arriving from astrophysical radio-bright objects drive stimulated decay in the Galactic halo creating a *countersource* with the dimensions and morphological features of each source in the...
Mrs
Ersilia Guarini
(Physics Department, University of Bari)
22/09/2020, 14:41
Cosmology & Astroparticle Physics
Axions can be produced in the Sun via the Primakoff process leading to conversions of thermal photons into axions in the flucutuating electric and magnetic fields generated by the charged particles in the stellar plasmas. Currently this flux is searched by the helioscope experiment CAST at CERN. A future generation helioscope experiment, called IAXO, is currently under investigation.
Seismic...
Mr
Stefan Stelzl
(TUM Munich)
22/09/2020, 14:54
Cosmology & Astroparticle Physics
We consider finite density effects in models with a metastable ground state. We find that sufficiently dense objects, such as neutron stars, can destabilise the metastable minimum allowing for classical formation of bubbles of a new vacuum. As we show, these bubbles are not necessarily confined to the dense region, but can escape to infinity. This leads to a phase transition in the universe...
Dr
Cem Eröncel
(DESY)
22/09/2020, 15:07
Cosmology & Astroparticle Physics
Axion-like-particle (ALP) is a well-motivated candidate for dark matter, and it is subject to extensive theoretical and experimental research in recent years. The ALP production mechanisms mostly studied in the literature are misalignment, thermal production in the plasma, and decay of cosmic strings. Recently, a new mechanism, axion fragmentation, has been proposed. It can arise if the axion...
Mr
Wolfram Ratzinger
(Johannes Gutenberg University Mainz)
22/09/2020, 15:20
Cosmology & Astroparticle Physics
Conventional approaches to probing axions and axion-like particles (ALPs) typically rely on a coupling to photons. However, if this coupling is extremely weak, ALPs become invisible and are effectively decoupled from the Standard Model. We show that such invisible axions, which are viable candidates for dark matter, can produce a stochastic gravitational wave background in the...
Yvette Welling
(DESY)
22/09/2020, 15:33
Cosmology & Astroparticle Physics
Axion inflation entails a coupling of the inflaton field to gauge fields through the Chern-Simons term. This results in a strong gauge field production during inflation, which backreacts on the inflaton equation of motion. We show that this strongly non-linear system generically experiences a resonant enhancement of the gauge field production, resulting in oscillatory features in the inflaton...
Miguel Escudero
(TUM)
22/09/2020, 16:45
Cosmology & Astroparticle Physics
At present, cosmological observations set the most stringent bound on the neutrino mass scale. Within the standard cosmological model (ΛCDM), the Planck collaboration reports $\Sigma m_\nu < 0.12$ eV at 95% CL. This bound, taken at face value, excludes many neutrino mass models. However, unstable neutrinos, with lifetimes shorter than the age of the universe $\tau_\nu < t_U$, represent a...
Mr
Sven Baumholzer
(Johannes Gutenberg-Universitaet Mainz)
22/09/2020, 16:58
Cosmology & Astroparticle Physics
In the framework of the scotogenic model, which features radiative generation of neutrino
masses, we explore light dark matter scenario. Throughout the paper we chiefly focus on
keV-scale dark matter which can be produced either via freeze-in through the decays of the
new scalars, or from the decays of next-to-lightest fermionic particle in the spectrum, which
is produced through...
Mr
Petter Taule
(Technical University of Munich)
22/09/2020, 17:11
Cosmology & Astroparticle Physics
Current and near future surveys are expected to map out the large-scale structure of the Universe at unprecedented precision. In order to extract information from observational data, a solid theoretical understanding is required, and in recent years considerable efforts has been dedicated to model the weakly non-linear regime using perturbative methods. In this talk, I will describe an...
Dr
Chandan Hati
(Technische Universität München, James-Franck-Straße 1, D-85748 Garching, Germany)
22/09/2020, 17:24
Cosmology & Astroparticle Physics
Neutron-antineutron ($n-\bar{n}$) oscillation violates baryon number by two units and an observable rate of such a process would strongly advocate physics beyond the Standard Model (BSM). Many prospective future experiments such as ESS and DUNE are planning to search for $n-\bar{n}$ oscillation improving on the current limits. In this talk, we will discuss the impact of the observation of...
Dr
Alexandra Dobrynina
(P. G. Demidov Yaroslavl State University & University of Hamburg)
22/09/2020, 17:37
Cosmology & Astroparticle Physics
An influence of a magnetic field on beta-processes is investigated under conditions of a core-collapse supernova. For realistic magnetic fields reachable in astrophysical objects we obtain simple analytical expressions for reaction rates of beta-processes as well as the energy and momentum transferred from neutrinos and antineutrinos to the matter. Based on the results of one-dimensional...
Mr
Pierluca Carenza
(Università degli Studi di Bari)
22/09/2020, 17:50
Cosmology & Astroparticle Physics
The cumulative emission of Axion-Like Particles (ALPs) from all past core-collapse supernovae (SNe) would lead to a diffuse flux with energies ${\mathcal O}(50)$ MeV. We use this to constrain ALPs featuring couplings to photons and to nucleons. ALPs coupled only to photons are produced in the SN core via the Primakoff process,and then converted into gamma rays in the Galactic magnetic field....
Mr
Henrique Rubira
(DESY)
22/09/2020, 18:03
Cosmology & Astroparticle Physics
LISA telescope will be specially interesting to probe the scenario of a first order phase transition happening close to the electroweak scale. Recently, it became evident that the main contribution to the GW spectra would come from the sound waves propagating through the plasma. Current estimates of the GW spectra are based on numerical simulations of a scalar field interacting with the plasma...
