2016/01/17 by Di Mauro, Mattia
#FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE)
paper · doi:10.48550/arxiv.1601.04323
The origin of the Isotropic Diffuse γ-Ray Background (IGRB) is one of the most intriguing mystery in astrophysics. Recently the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has measured the IGRB spectrum from 100 MeV to 820 GeV. Thousands of extragalactic sources are detected at γ-ray energies and, thanks to Fermi-LAT catalogs and to population studies, we show that the IGRB can be explained, in the entire energy range, by the γ-ray emission from unresolved misaligned Active Galactic Nuclei, blazars and Star Forming Galaxies. Finally we derive, with a dedicated analysis based on the 2FHL Fermi-LAT catalog at E>50 GeV, the intrinsic source count distribution of blazars and demonstrate that this source population explains the 86+16-14% of the total extragalactic γ-ray background.