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Title: Fermi-LAT γ-ray anisotropy and intensity explained by unresolved radio-loud active galactic nuclei

Radio-loud active galactic nuclei (AGN) are expected to contribute substantially to both the intensity and anisotropy of the isotropic γ-ray background (IGRB). In turn, the measured properties of the IGRB can be used to constrain the characteristics of proposed contributing source classes. We consider individual subclasses of radio-loud AGN, including low-, intermediate-, and high-synchrotron-peaked BL Lacertae objects, flat-spectrum radio quasars, and misaligned AGN. Using updated models of the γ-ray luminosity functions of these populations, we evaluate the energy-dependent contribution of each source class to the intensity and anisotropy of the IGRB. We find that collectively radio-loud AGN can account for the entirety of the IGRB intensity and anisotropy as measured by the Fermi Large Area Telescope (LAT). Misaligned AGN provide the bulk of the measured intensity but a negligible contribution to the anisotropy, while high-synchrotron-peaked BL Lacertae objects provide the dominant contribution to the anisotropy. In anticipation of upcoming measurements with the Fermi-LAT and the forthcoming Cherenkov Telescope Array, we predict the anisotropy in the broader energy range that will be accessible to future observations.
Authors:
; ;  [1] ;  [2]
  1. Dipartimento di Fisica, Università di Torino, via P. Giuria 1, Torino, 10125 Italy (Italy)
  2. California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125 (United States)
Publication Date:
OSTI Identifier:
22375750
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 11; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; BL LACERTAE OBJECTS; ENERGY DEPENDENCE; ENERGY RANGE; FUNCTIONS; GALAXY NUCLEI; LUMINOSITY; PEAKS; QUASARS; SPECTRA; SYNCHROTRONS; TELESCOPES