Related papers: Cosmic Rays: Recent Progress and some Current Ques…
The origin of Galactic cosmic rays is still a burning question that forms a major motivation for developments in ground-based gamma-ray astronomy. SNRs are long-thought to be sites for the acceleration of Galactic cosmic rays, and evidence…
A "knee" in the cosmic-ray spectrum, characterized by a sudden steepening of the spectral shape at $\sim 4$ PeV, may be interpreted either as a global feature of Galactic cosmic rays or as a local signature. In the former scenario,…
The sharp change in slope of the ultrahigh energy cosmic ray (UHECR) spectrum around 10^18.6 eV (the ankle), combined with evidence of a light but extragalactic component near and below the ankle and intermediate composition above, has…
We note that antishadowing could help in the explanation of cosmic rays phenomena such as knee in the energetic spectrum and existence of penetrating and long-flying particles.
We examine the first order Fermi acceleration on the presumption that supernova remnant shocks cross ambient magnetic fields with various angles. These oblique shocks accelerate particles more efficiently than the parallel shocks and…
The origin of the knee in cosmic ray spectrum remains to be an unsolved fundamental problem. There are various kinds of models which predict different break positions and the compositions of the knee. In this work, we suggest to use diffuse…
Galactic cosmic rays (CRs) are accelerated at the forward shocks of supernova remnants (SNRs) via diffusive shock acceleration (DSA), an efficient acceleration mechanism that predicts power-law energy distributions of CRs. However,…
The energy range encompassing the ankle of the cosmic ray energy spectrum probably marks the exhaustion of the accelerating sources in our Galaxy, as well as the end of the Galactic confinement. Furthermore, this is the region where the…
Supernova Remnants (SNRs) are broadly accepted as the main accelerators of Galactic cosmic rays (GCRs) with energies up to the knee region. Recent measurements of pion bumps in IC 443 and W 44 by Fermi-LAT show indirect evidence of the…
Our purpose is to evaluate the rate of the maximum energy and the acceleration rate that cosmic rays acquire in the non-relativistic diffusive shock acceleration as it could apply during their lifetime in various astrophysical sites, where…
The maximum cosmic ray energy achievable by acceleration by a relativistic blast wave is derived. It is shown that forward shocks from long GRB in the interstellar medium are powerful enough to produce the Galactic cosmic-ray component up…
It is widely believe that galactic cosmic rays are originated in supernova remnants (SNRs) where they are accelerated by diffusive shock acceleration process at supernova blast waves driven by expanding SNRs. In recent theoretical…
In models with extra dimensions the fundamental scale of gravity M_D could be of order TeV. In that case the interaction cross section between a cosmic proton of energy E and a dark matter particle \chi will grow fast with E for center of…
From the data on Cherenkov light from EASs collected over the period of more than 15 years, the spectrum of cosmic rays was obtained in the energy range 1.0E15-1.0E18 eV. This spectrum has two features: at ~3.0E15 eV (first knee) and at…
The transition from galactic to extragalactic cosmic rays is discussed. One of critical indications for transition is given by the Standard Model of Galactic cosmic rays, according to which the maximum energy of acceleration for iron nuclei…
The sources of cosmic rays between the knee and the ankle are still debated. The Galactic wind and its termination shock have been proposed to contribute to this transition between Galactic and extragalactic origin, but another possibility…
We consider the galactic population of gamma-ray pulsars as possible sources of cosmic rays at and just above the ``knee'' in the observed cosmic ray spectrum at $10^{15}$--$10^{16}$ eV. We suggest that iron nuclei may be accelerated in the…
The measurement of cosmic ray energy spectra, in particular for individual species, is an essential approach in finding their origin. Locating the "knees" of the spectra is an important part of the approach and has yet to be achieved. Here…
Increasing observational evidence gathered especially in X-rays and gamma-rays during the course of the last few years support the notion that Supernova remnants (SNRs) are Galactic particle accelerators up to energies close to the ``knee''…
Results from the KASCADE air shower experiment investigating the origin of cosmic rays in the energy region from 10^13 to 10^17 eV are presented. Attention is drawn on the investigation of interactions in the atmosphere and the energy…