arXiv subjects

Anna Uryson

Publications and source records attributed to Anna Uryson.

4 recordsLinked to original sources

arXiv2026

Possible Sources of Iron Nuclei in Ultra-High-Energy Cosmic Rays

The origin of a cosmic ray particle with an ultra-high energy of 2.44 x 10^20 eV recorded by the Telescope Array is discussed by assuming that it is a heavy nucleus, namely an iron or silicon nucleus. Iron is chosen as a heaviest element in cosmic rays, while silicon is chosen to find out how much the theoretical results obtained vary with the mass of the heavy nucleus. Assuming extragalactic origin of the particle with such energy, the constraints on the distances to possible sources are analysed using a routine calculation of the cosmic ray propagation in extragalactic space. These possible sources are discussed.

astro-ph.HE↗

arXiv2022

Studying cosmic ray sources using intergalactic electromagnetic cascades

In this paper intergalatic electromagnetic cascades are used as a probe of cosmic ray sources. This is achieved as follows. In extragalactic space cosmic rays initiate electromagnetic cascades in which gamma-ray and neutrino emission arises. We used the joint analysis of cosmic ray data, along with extragalactic gamma-ray and neutrino emission, to study particle acceleration in the vicinity of supermassive black holes. Particle injection spectra depend on processes of particle acceleration, and here we discuss models with various injection spectra. The computation of the propagation of cosmic rays in space were performed using the publicly avaliable TransportCR code. It was found that a new subclass of sources might exist that does not contribute to the particle flux on Earth, instead to gamma-ray and neutrino emissions arising in electromagnetic cascades. In addition, the upper limit of the relative number of 'exotic' supermassive black holes surrounded by a superstrong magnetic field is derived.

astro-ph.HE↗

arXiv2022

Influence of extragalactic magnetic fields on extragalactic cascade gamma-ray emission

We discuss the influence of extragalactic magnetic fields on the intensity of gamma-ray emission produced in electromagnetic cascades from ultra-high energy cosmic rays propagating in extragalactic space. Both cosmic rays and cascade particles propagate mostly out of galaxies, galactic clusters, and large scale structures as their relative volume is small. Therefore their magnetic fields weakly affect emission produced in cascades. Yet estimates of this influence can be useful searching for dark matter particles, when components of extragalactic gamma-ray background should be known, including cascade gamma-ray emission. To study magnetic field influence on cascade emission we analyze cosmic particle propagation in fields of ~10^(-6) and 10^(-12) G (the former is typical inside galaxies and clusters and the latter is common in voids and outside galaxies and clusters). The calculated spectra of cascade gamma-ray emission are similar in the range of ~10^7-10^9 eV. So analyzing cascade emission in this range it is not necessary to specify models of extragalactic magnetic field.

astro-ph.HE↗

arXiv2018

Contribution of Cosmic Rays from Sources with a Monoenergetic Proton Spectrum to the Extragalactic Diffuse Gamma-Ray Emission

The extragalactic sources of ultra-high-energy (E > 4x10^19 eV) cosmic rays that make a small contribution to the flux of particles recorded by ground-based arrays are discussed. We show that cosmic rays from such sources can produce a noticeable diffuse gamma-ray flux in intergalactic space compared to the the data obtained with Fermi LAT (onboard the Fermi space observatory). A possible type of active galactic nuclei (AGNs) in which cosmic-ray protons can be accelerated to energies 1021 eV is considered as an illustration of such sources. We conclude that ultra-high-energy cosmic rays from the AGNs being discussed can contribute significantly to the extragalactic diffuse gamma-ray emission. In addition, a constraint on the fraction of the AGNs under consideration relative to the BL Lac objects and radio galaxies has been obtained from a comparison with the Fermi LAT data.

astro-ph.HE↗