2013/04/30 by M. Di Mauro, F. Calore, F. Donato +2 · 1 citation
Physics and Astronomy · #astro-ph.CO #astro-ph.HE #hep-ph
paper · pdf · doi:10.1088/0004-637x/780/2/161
Accepted for publication in ApJ
arxiv created 2013/11/18 · arxiv updated 2015/06/15
Active galactic nuclei (AGN) with jets seen at small viewing angles are the most luminous and abundant objects in the γ-ray sky. AGN with jets misaligned along the line-of-sight appear fainter in the sky, but are more numerous than the brighter blazars. We calculate the diffuse γ-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 γ-ray luminosity and the radio-core luminosity is established and demonstrated to be physical by statistical tests, as well as compatible with upper limits based on \it Fermi-LAT data for a large sample of radio-loud MAGN. We constrain the derived γ-ray luminosity function by means of the source count distribution of the radio galaxies (RGs) detected by the \it Fermi-LAT. We finally calculate the diffuse γ-ray flux due to the whole MAGN population. Our results demonstrate that the MAGN can contribute from 10% up to nearly the entire measured Isotropic Gamma-Ray Background (IGRB). We evaluate a theoretical uncertainty on the flux of almost an order of magnitude.