41 research outputs found
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.Comment: 14 pages, 5 fig. To be Published in Astronomy Letters, 2004, v.30,
#1
Declination dependence of the cosmic-ray flux at extreme energies
We study the large-scale distribution of the arrival directions of the
highest energy cosmic rays observed by various experiments. Despite clearly
insufficient statistics, we find a deficit of cosmic rays at energies higher
than 10^{20} eV from a large part of the sky around the celestial North Pole.
We speculate on possible explanations of this feature.Comment: 5 pages, 4 figures; v2: 11 pages, 4 figures, title changed (to avoid
confusion with the Southern hemisphere), analysis extended, more data
included, results unchanged; to be published in JCA