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A. V. Uryson

Publications and source records attributed to A. V. Uryson.

7 recordsLinked to original sources
arXiv2017

The Possibility of Investigating Ultra-High-Energy Cosmic-Ray Sources Using Data on the Extragalactic Diffuse Gamma-Ray Emission

We provide our estimates of the intensity of the gamma-ray emission with an energy near 0.1 TeV generated in inrergalactic space in the interactions of cosmic rays with background emissions. We assume that the cosmic ray sources are point-like and these are active galactic nuclei. The following pjssible types of sources are considered: remote and powerful ones, at redshifts up to z=1.1, with a monoenergetic particle spectrum, E=10^21 eV; the same objects, but with a power-law particle spectrum; and nearby sources with redshifts 0<z<=0.0092, i.e. at distances no larger than 50 Mpc also with a power-law particle spectrum. The contribution of cosmic rays to to the extragalactic diffuse gamma-ray background at an energy of 0.1 TeV has been found to depend on the type of sources or, more specifically, the contribution ranges from f<<10^(-4) to f of about 0.1. depending on the source model. We conclude that the data on the extragalactic background gamma-ray emission can be used to determine the characteristics of cosmic-ray sources, i.e. their distances and the pattern of the particle energy spectrum. Keywords: cosmic rays, diffuse gamma-ray emission, active galactic nuclei. To be published in: Astronomy Letters, 2017, vol. 43, No.8, pp. 529-535.

astro-ph.HE↗
arXiv2015

Investigation of Cosmic-Ray Sources with Gamma-Ray Initiated Showers

A new method of investigating ultra-high energy cosmic ray sources is suggested. The method is based on analysis of gamma-ray emission that is generated in extragalactic space when ultra-high energy cosmic particles interact with cosmic background. We have found that intensity of the gamma-ray emission depends on characteristics of cosmic ray sources, specifically on their remoteness and initial particle energy spectra. In the Earth atmosphere cosmic rays initiate air showers, therefore selecting quanta-initiated showers (and excluding those from the galactic plane, gamma-ray sources, etc.) we can obtain above mentioned source characteristics. We derive that the number of quanta-initiated showers is 0 or ~3x1000 depending on source parameters, typical statistics of showers registered at 10^14 eV being of ~10^8. The difference is large enough to use this method for studying ultra-high energy cosmic ray sources.

astro-ph.HE↗
arXiv2005

Possible Origin of Clusters in Ultra-High-Energy Cosmic rays

We estimate the detection rate of ultrahigh-energy cosmic rays on ground based arrays by assuming that the cosmic ray sources are active galactic nuclei. We analyse the cases of detection of clusters, several particles that arrived, within the error limits, from the same area of the sky. The adopted model is shown to explain the detection rate of clusters on the AGASA array.

astro-ph↗
arXiv2004

The Maximum Energy and Spectra of Cosmic Rays Accelerated in Active Galactic Nuclei

We computed the energy spectra of the incident (on an air shower array) ultrahigh-energy (E > 4x10^19 eV) cosmic rays (CRs) that were accelerated in nearby Seyfert nuclei at redshifts z<= 0.0092 and in BL Lac objects. For our calculations, we took the distribution of these sources over the sky from catalogs of active galactic nuclei. In accordance with the possible particle acceleration mechanisms, the initial CR spectrum was assumed to be monoenergetic for BL Lac's and a power law for Seyfert nuclei. The CR energy losses in intergalactic space were computed by the Monte Carlo method. The artificial proton statistic was 10^5 for each case considered. The computed spectra of the particles incident on an air shower array agree with the measurements, which indirectly confirms the adopted acceleration models. At energies E>=10^20 eV, the spectrum of the protons from nearby Seyfert nuclei that reached an air shower array closely matches the spectrum of the particles from BL Lac's. BL Lac's are, on average, several hundred Mpc away. Therefore, it is hard to tell whether a blackbody cutoff exists or not by analyzing the shape of the measured spectrum at E>= 5x10^19 eV.

astro-ph↗
arXiv2004

Possible Spectra of Cosmic Rays Accelerated in Extragalactic Sources

Spectra at the Earth of ultra-high energy cosmic rays (UHECR) from Seyfert nuclei with red shifts z<=0.0092 and from Blue Lacertae objects (BL Lac's) are calculated. The spectra are compared with the experimental data. It is shown that in nearby Seyferts the initial spectrum of the UHECRs is most likely the exponential one. UHECRs from BL Lac's may have the monoenergetic initial spectrum with the energy of 10^21 eV to fit to the data. Spectra at the Earth derived in these two models are very similar if there is no Bl Lac's with red shifts z<0.02. The maximal energy in cosmic rays seemingly does not exceed 10^21 eV. In calculations we used red shift distributions of the objects according to the recent (2001) catalogue of active nuclei by Veron-Cetty and Veron (see ref. in the text).

astro-ph↗
arXiv2003

Identification of Nearby Active Galaxies as Sources of Cosmic Rays Above 4x10^19 ev

Arrival directions of 63 extensive air showers with energies 4 10^19 3 sigma (sigma is the parameter of Gaussian distribution)for Seyfert galaxies with redshifts z<0.01. The Seyfert galaxies are characterized by moderate luminosities (L<10^46 erg/s) and weak radio and X-ray emission. Astronomical and Astrophysical Transactions, 2003, v.22, #6, pp.(TBD)

astro-ph↗