Related papers: The diffuse $\gamma$-ray background is dominated b…
The propagation of particles accelerated at supernova remnant shocks and escaping the parent remnants is likely to proceed in a strongly non-linear regime, due to the efficient self-generation of Alfv\'en waves excited through streaming…
The Fermi gamma-ray satellite has recently detected gamma-ray emissions from radio galaxy cores. From these samples, we first examine the correlation between the luminosities at 5 GHz, L_{5GHz}, and at 0.1-10 GeV, L_{gamma}, of these…
We present a semi-empirical model for the evolving far-infrared to ultraviolet diffuse background produced by stars in galaxies. The model is designed to reproduce the results of deep galaxy surveys, and therefore may be considered as a…
The light emitted by all galaxies over the history of the Universe produces the extragalactic background light (EBL) at ultraviolet, optical, and infrared wavelengths. The EBL is a source of opacity for $\gamma$ rays via photon-photon…
Continuum gamma-ray emission produced by interactions of cosmic rays with interstellar matter and radiation fields is a probe of non-thermal particle populations in galaxies. After decades of continuous improvements in experimental…
For more than a decade now the complete origin of the diffuse gamma-ray emission background (EGRB) has been unknown. Major components like unresolved star-forming galaxies (making <50% of the EGRB) and blazars (<23%), have failed to explain…
The contribution of the Source Cosmic Rays (SCRs), confined in Supernova Remnants, to the diffuse high energy \gr emission above 1 GeV from the Galactic disk is studied. \grs produced by the SCRs have a much harder spectrum compared with…
Starburst galaxies have a highly increased star-formation rate compared to regular galaxies and inject huge amounts of kinetic power into the interstellar medium via supersonic stellar winds, and supernova explosions. Supernova remnants,…
Cosmic rays, along with stellar radiation and magnetic fields, are known to make up a significant fraction of the energy density of galaxies such as the Milky Way. When cosmic rays interact in the interstellar medium, they produce gamma-ray…
The isotropic gamma-ray background arises from the contribution of unresolved sources, including members of confirmed source classes and proposed gamma-ray emitters such as the radiation induced by dark matter annihilation and decay. Clues…
We present new theoretical estimates of the relative contributions of unresolved blazars and star-forming galaxies to the extragalactic gamma-ray background (EGB) and discuss constraints on the contributions from alternative mechanisms such…
Recent radio surveys have discovered a large number of low luminosity core dominated radio galaxies that are much more abundant than those at higher luminosities. These objects will be too faint in gamma-rays to be detected individually by…
The contribution of unresolved sources to the diffuse gamma-ray background could produce anisotropies in this emission on small angular scales. Recent studies have considered the angular power spectrum and other anisotropy metrics as tools…
The impact of non-thermal processes on the spectral energy distributions of galaxies can be dramatic, but such processes are often neglected in considerations of their structure and evolution. Particle acceleration associated with high mass…
Gamma rays from young pulsars and milli-second pulsars are expected to contribute to the diffuse gamma-ray emission measured by the {\it Fermi} Large Area Telescope (LAT) at high latitudes. We derive the contribution of the pulsars…
The gamma-ray sky >100 MeV is dominated by the diffuse emissions from interactions of cosmic rays with the interstellar gas and radiation fields of the Milky Way. Observations of these diffuse emissions provide a tool to study cosmic-ray…
We calculate the diffuse $\gamma$-ray emission due to the population of misaligned AGN (MAGN) unresolved by the Large Area Telescope (LAT) on the {\it Fermi} Gamma-ray Space Telescope ({\it Fermi}). A correlation between the $\gamma$-ray…
Using the cosmic ray (CR) data available in the energy interval $(10 - 2 \times 10^{7})$ GeV/particle, we have calculated the profile of the primary $\gamma$-ray spectrum produced by the interaction of these CR with thermal nuclei of the…
The enigma of cosmic ray origin and propagation stands as a key question in particle astrophysics. The precise spatial and spectral measurements of diffuse Galactic gamma-ray emission provide new avenues for unraveling this mystery. Based…
The diffuse extragalactic background light consists of the sum of the starlight emitted by galaxies through the history of the Universe, and it could also have an important contribution from the first stars, which may have formed before…