Related papers: On the Physics Connecting Cosmic Rays and Gamma Ra…
We have developed a model which aims to reproduce observational data of many kinds related to cosmic-ray origin and propagation: direct measurements of nuclei, antiprotons, electrons and positrons, gamma-rays, and synchrotron radiation. Our…
Gamma-ray telescopes have reported some surprising observations of multi-TeV photons from distant active galactic nuclei (AGN), which show no significant attenuation due to pair production on either the extragalactic background light (EBL),…
Interstellar synchrotron emission depends on Galactic magnetic fields and on cosmic-ray leptons. Observations of radio emission are an important tool for studying cosmic-ray propagation models and interstellar electron spectrum and…
Nearby sources of cosmic rays up to a ZeV(=10^21 eV) could be observed with a multi-messenger approach including secondary gamma-rays and neutrinos. If cosmic rays above ~10^18 eV are produced in magnetized environments such as galaxy…
We consider a cosmic ray spectrum that is a power law in momentum down to a cutoff and derive a lower cutoff corresponding to $E_{kin} \sim (30-60)$ MeV from the observed ionization rates in nearby diffuse clouds. While the real spectra of…
It has been suggested that high-energy gamma-ray emission ($>100{\rm MeV}$) of nearby star-forming galaxies may be produced predominantly by cosmic rays colliding with the interstellar medium through neutral pion decay. The pion-decay…
Cosmic rays are particles (mostly protons) accelerated to relativistic speeds. Despite wide agreement that supernova remnants (SNRs) are the sources of galactic cosmic rays, unequivocal evidence for the acceleration of protons in these…
The MAGIC Collaboration has provided new observational data pertaining to the TeV J2032+4130 gamma-ray source (within the Cygnus OB2 region), for energies E_gamma >400 GeV. It is then appropriate to update the impact of these data on…
The Fermi Gamma-ray Space Telescope has revealed a diffuse $\gamma$-ray background at energies from 0.1 GeV to 1 TeV, which can be separated into Galactic emission and an isotropic, extragalactic component. Previous efforts to understand…
Calculations of the expected TeV $\gamma$-ray emission, produced by accelerated cosmic rays (CRs) in nuclear collisions, from supernova remnants evolving in a uniform interstellar medium (ISM) are presented. The aim is to study the…
The diffuse $\gamma$-ray spectrum at sub-PeV energy region has been measured for the first time by the Tibet-AS$\gamma$ experiment. It will shed new light on the understanding of origin and propagation of Galactic cosmic rays at very high…
The solar disk is a bright source of multi-GeV gamma rays, due to the interactions of hadronic cosmic rays with the solar atmosphere. However, the underlying production mechanism is not understood, except that its efficiency must be greatly…
Interaction of cosmological gamma ray burst radiation with the dense interstellar medium of host galaxy is considered. Gas dynamical motion of interstellar medium driven by gamma ray burst is investigated in 2D approximation for different…
We discuss expectations for the absorption of high-energy gamma-rays by gamma-gamma pair production with intergalactic radiation fields (IRFs) at very high redshifts (z~5-20), and the prospects thereof for probing the cosmic reionization…
Diffuse Galactic gamma-ray emission is produced in interactions of cosmic rays with gas and ambient photon fields and thus provides us with an indirect measurement of cosmic rays in various locations in the Galaxy. The diffuse gamma-ray…
We show in this letter that estimates of the local emissivity of {\gamma}-rays in the GeV-TeV range suffer uncertainties which are of the same order of magnitude as the current Fermi results. Primary cosmic-ray fluxes, cosmic-ray…
The spectral data on the diffuse Galactic gamma-rays, at medium and high latitudes (|b| > 10) and energies of 1-100 GeV, recently published by the Fermi Collaboration are used to produce a novel study on the gamma-ray emissivity in the…
An important contribution to the gamma-ray emission of our Galaxy is the Galactic Diffuse emission. We present specific developments within the PICARD code for modeling of Galactic cosmic ray propagation that are relevant for the…
We are constructing a model which aims to reproduce observational data of many kinds related to cosmic-ray origin and propagation: direct measurements of nuclei, antiprotons, electrons and positrons, gamma-rays, and synchrotron radiation.…
Interactions of grazing incidence, ultra high energy cosmic rays with the earth's atmosphere may provide a new method of studying energetic cosmic rays with gamma-ray satellites. It is found that these cosmic ray interactions may produce…