Related papers: Gamma-ray induced cascades and magnetic fields in …
The extragalactic magnetic field could be detected by searching for signatures of the electromagnetic cascade initiated by high-energy photons on the intergalactic radiation and deflected by the field. This process produces a time delay and…
Relativistic pair beams created in the intergalactic medium (IGM) by TeV gamma rays from blazars are expected to produce a detectable GeV-scale electromagnetic cascade, but the cascade component is absent in the spectra of many…
We review extragalactic $\gamma$-ray propagation models with emphasis on the electromagnetic (EM) cascade process in the magnetized expanding Universe. We consider cascades initiated by primary protons of ultra-high energy accelerated by…
The universe is filled with a diffuse and isotropic extragalactic background of gamma-ray radiation, containing roughly equal energy flux per decade in photon energy between 3 MeV-100 GeV. The origin of this background is one of the…
Gamma rays from TeV blazars have been detected by ground-based experiments for more than two decades. We have collected the most extensive set of archival spectra from these sources in order to constrain the processes affecting gamma-ray…
Galactic cosmic rays are believed to be mostly accelerated at supernova shocks. However, the interstellar magnetic field is too weak to efficiently accelerate galactic cosmic rays up to the highest energies, i.e. $10^{15}$ eV. A stronger…
We consider the neutron star (NS) of the magnetar type inside the massive binary system. We determine the conditions under which the matter from the stellar wind can penetrate the inner magnetosphere of the magnetar. At some distance from…
The injection of ultra-high energy cosmic rays in the intergalactic medium leads to the production of a GeV-TeV gamma-ray halo centered on the source location, through the production of a high electromagnetic component in the interactions…
Constraining the behavior of cosmic ray data observed at Earth requires a precise understanding of how the cosmic rays propagate in the interstellar medium. The interstellar medium is not homogeneous; although turbulent magnetic fields…
The bulk of the diffuse galactic gamma-ray emission above a few tens of GeV has been conventionally ascribed to the decay of neutral pions produced in cosmic-ray interactions with interstellar matter. Cosmic-ray electrons may, however, make…
The very short time scale variability of TeV $\gamma$-ray emission from active galaxies suggests that the acceleration process of particles and the production of primary $\gamma$-rays likely occurs relatively close to the accretion disk. We…
We have used a Monte Carlo simulation of a Polar Cap (PC) model of gamma-ray pulsars to estimate light curves and phase-resolved spectra for sources whose rotational and magnetic axes are oriented so that only one of the magnetic poles…
Recent gamma-ray observations have detected photons up to energies of a few PeV. These highly energetic gamma rays are emitted by the most powerful sources in the Galaxy. Propagating over astrophysical distances, gamma rays might interact…
Using the analytic modeling of the electromagnetic cascades compared with more precise numerical simulations we describe the physical properties of electromagnetic cascades developing in the universe on CMB and EBL background radiations. A…
We investigate numerically the contribution to the cosmic gamma-ray background from cosmic-rays ions and electrons accelerated at intergalactic shocks associated with cosmological structure formation. We show that the kinetic energy of…
We present a very brief overview of some recent gamma-ray observations of selected blazars to reveal an indication for a considerable or even dominant contribution of secondary gamma-rays from electromagnetic cascades to the observable…
Recent observations of isotropic diffuse backgrounds by Fermi and IceCube allow us to get more insight into distant very-high-energy (VHE) and ultra-high-energy (UHE) gamma-ray/neutrino emitters, including cosmic-ray accelerators/sources.…
We investigate the cosmic ray driven dynamo in the interstellar medium of irregular galaxy. The observations (Chyzy et al. 2000, 2003) show that the magnetic field in irregular galaxies is present and its value reaches the same level as in…
An intergalactic magnetic field stronger than $3\times10^{-13}$~G would explain the lack of a bright, extended degree-scale, GeV-energy inverse Compton component in the gamma-ray spectra of TeV-blazars. A robustly predicted consequence of…
Very high energy (VHE; energy $E \gtrsim 100\,$GeV) $\gamma$-rays originating from extragalactic sources undergo pair production with low-energy photons of background radiation fields. These pairs can inverse-Compton-scatter background…