Related papers: Gamma-Rays from Star Forming Activity Appear to Ou…
We study the possibility that the $\gamma$-ray loud active galactic nuclei (AGN) are the sources of ultra-high energy cosmic rays (UHECR), through the correlation analysis of their locations and the arrival directions of UHECR. We use the…
We present an ISO SWS and ISOPHOT-S, mid-infrared spectroscopic survey of 15 ultra-luminous IRAS galaxies. We combine the survey results with a detailed case study, based on near-IR and mm imaging spectroscopy, of one of the sample galaxies…
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…
In the paper, we continually use the method of image stacking to study the origin of the extragalactic gamma-ray background (EGB) at GeV bands, and find that the Faint Images of the Radio Sky at Twenty centimeters (FIRST) sources undetected…
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…
We present a model for estimating the blazar contribution to the extragalactic gamma-ray background (EGRB) in the EGRET energy range. It is based on inverse-Compton scattering as the dominant gamma-ray production process in the jets of flat…
Inverse Compton scattering by relativistic electrons produces a major component of the diffuse emission from the Galaxy. The photon fields involved are the cosmic microwave background and the interstellar radiation field from stars and…
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…
The diffuse gamma-ray background radiation (GBR) at high Galactic latitudes could be dominated by inverse Compton scattering (ICS) of cosmic ray (CR) electrons on the cosmic microwave background radiation (CBR) and on starlight (SL) in an…
We have computed the 15 microns integrated galaxy light produced by ISOCAM galaxies above a sensitivity limit of 50 microJy. It sets a lower limit to the 15 microns extragalactic background light of (2.4+/-0.5) nW/m^2/Hz. The redshift…
Following our previously proposed technique, we have used the recent gamma-ray observations of Mrk 421 to place theoretically significant constraints on and possible estimates of the intergalactic infrared radiation field (IIRF) which are…
TeV gamma rays emitted by GRBs are converted into electron-positron pairs via interactions with the extragalactic infrared radiation fields. In turn the pairs produced, whose trajectories are randomized by magnetic fields, will inverse…
Star-forming galaxies (SFGs) are a subclass of $\gamma$-ray emitters and a correlation between their $\gamma$-ray luminosity ($L_{\rm \gamma}$) and the total infrared (IR) luminosity ($L_{\rm IR}$) has been established based on the Fermi…
We report on the first Fermi Large Area Telescope (LAT) measurements of the so-called "extra-galactic" diffuse gamma-ray emission (EGB). This component of the diffuse gamma-ray emission is generally considered to have an isotropic or nearly…
We study the origin of the extragalactic diffuse gamma-ray background using the data from the Fermi telescope. To estimate the background level, we count photons at high Galactic latitudes |b|>60 degrees. Subtracting photons associated to…
We have incorporated the description of the X-ray properties of Active Galactic Nuclei (AGNs) into a semi-analytic model of galaxy formation, adopting physically motivated scaling laws for accretion triggered by galaxy encounters. Our model…
The effect of Active Galactic Nuclei (AGN) on their host galaxies -- in particular their levels of star formation -- remains one of the key outstanding questions of galaxy evolution. Successful cosmological models of galaxy evolution…
We argue that gamma-ray bursts (GRBs) may be the origin of the cosmic gamma-ray background radiation observed in GeV range. It has theoretically been discussed that protons may carry a much larger amount of energy than electrons in GRBs,…
Structure formation in the universe can produce high energy gamma-rays from shock-accelerated electrons, and this process may be the origin of the extragalactic gamma-ray background (EGRB) as well as a part of the unidentified sources…
Active galactic nuclei (AGN) are believed to be promising candidates of extragalactic cosmic-ray accelerators and sources, and associated high-energy neutrino and hadronic gamma-ray emission has been studied for many years. We review models…