Related papers: Particle acceleration in relativistic subluminal s…
A property common to several different astrophysical sources of high-energy gamma-rays is the presence of bulk motion at relativistic speed. The intrinsic spectra of the nonthermal radiating particles also show interesting similarities,…
The extragalactic background (EGB) of diffuse gamma rays can be determined by subtracting the Galactic contribution from the data. This requires a Galactic model (GM) and we include for the first time the contribution of dark matter…
Recent progress in cosmic ray physics covering the energy range from about 10^{14} eV to 10^{19} eV is reviewed. The most prominent features of the energy spectrum are the so called `knee' at E ~ 3 * 10^{15} eV and the `ankle' at few…
We calculate the spectrum of blast wave models of gamma-ray burst sources, for various assumptions about the magnetic field density and the relativistic particle acceleration efficiency. For a range of physically plausible models we find…
The Extragalactic Background Light (EBL) from the infrared (IR) through the ultraviolet (UV) is dominated by emission from stars, either directly or through absorption and reradiation by dust. It can thus give information on the star…
Analysis of the experimental data on cosmic ray spectra in the framework of the proposed model with two types of sources leads to conclusion, that sources with particle generation spectral exponent $p\sim 2.85$ give the major contribution…
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…
It is shown that the acceleration of particles by a powerful relativistic jet associated with the activity of a supermassive black hole in the Galactic center several million years ago may explain the observed cosmic ray spectrum at…
Gamma-ray bursts are known to be sources of high-energy gamma rays, and are likely to be sources of high-energy cosmic rays and neutrinos. Following a short review of observations of GRBs at multi-MeV energies and above, the physics of…
Shocks in jets and hot spots of Active Galactic Nuclei (AGN) are one prominent class of possible sources of very high energy cosmic ray particles (above 10^18eV). Extrapolating their spectrum to their plausible injection energy from some…
Cosmological $\gamma$-ray bursts originate from relativistic winds. Temporal fluctuations in the wind velocity can give rise to internal shocks which dissipate a significant fraction of the wind kinetic energy. Part of the energy dissipated…
Cosmic rays around the so-called knee in the spectrum at around PeV primary energy are generally galactic in origin. Observations on the form of their energy spectrum and their mass composition are fundamental tools to understand the…
The principal paradigm for gamma-ray bursts (GRBs) suggests that the prompt transient gamma-ray signal arises from multiple shocks internal to the relativistic expansion. This paper explores how GRB prompt emission spectra can constrain…
Accretion flows onto supergalactic-scale structures are accompanied with large spatial scale shock waves. These shocks were postulated as possible sources of ultra-high energy cosmic rays. The highest particle energies were expected for…
The cosmic rays spectrum has been shown to extend well beyond 10^20 eV. With nearly 20 events observed in the last 40 years, it is now established that particles with energies near or above 10^21 eV. No nearby astrophysical object has been…
Supernova remnants have long been regarded as sources of the Galactic cosmic rays up to petaelectronvolts, but convincing evidence is still lacking. In this work we explore the common origin of the subtle features of the cosmic ray spectra,…
We investigate how the extragalactic proton component derived within the "escape model" can be explained by astrophysical sources. We consider as possible cosmic ray (CR) sources normal/starburst galaxies and radio-loud active galactic…
We discuss processes in galactic cosmic ray (GCR) acceleration sites - supernova remnants, compact associations of young massive stars, and superbubbles. Mechanisms of efficient conversion of the mechanical power of the outflows driven by…
The existence of the spectral break around $\sim 3 \times 10^{15}$ eV in the cosmic ray spectrum (referred to as the `knee') is one of the biggest questions in cosmic ray astrophysics. At the same time, the origin of cosmic rays above the…
I develop a theory to account for the cosmic ray spectrum. The essential assumption is that, due to fast convective motions, the free mean path perpendicular to the magnetic field is independent of energy and has the scale of the thickness…