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

Di Mauro, Mattia and Cuoco, Alessandro and Donato, Fiorenza and Siegal-Gaskins, Jennifer M. (2014) Fermi-LAT γ-ray anisotropy and intensity explained by unresolved radio-loud active galactic nuclei. Journal of Cosmology and Astroparticle Physics, 2014 (11). Art. No. 21. ISSN 1475-7516. doi:10.1088/1475-7516/2014/11/021.

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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.

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Additional Information:© 2014 IOP Publishing Ltd and Sissa Medialab. Received July 21, 2014. Revised October 3, 2014. Accepted October 24, 2014. Published November 17, 2014. We thank Pasquale D. Serpico and Hannes Zechlin for useful discussions and a careful reading of the manuscript. This work is supported by the research grant TAsP (Theoretical Astroparticle Physics) funded by the Istituto Nazionale di Fisica Nucleare (INFN), by the Strategic Research Grant: Origin and Detection of Galactic and Extragalactic Cosmic Rays funded by Torino University and Compagnia di San Paolo, by the Spanish MINECO under grants FPA2011-22975 and MULTIDARK CSD2009-00064 (Consolider-Ingenio 2010 Programme), by Prometeo/2009/091 (Generalitat Valenciana), and by the EU ITN UNILHC PITN-GA-2009-237920. At LAPTh this activity was supported by the Labex grant ENIG-MASS. JSG acknowledges support from NASA through Einstein Postdoctoral Fellowship grant PF1-120089 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060.
Funding AgencyGrant Number
Istituto Nazionale di Fisica Nucleare (INFN)TAsP
Torino UniversityUNSPECIFIED
Compagnia di San PaoloUNSPECIFIED
Spanish MINECOFPA2011-22975
Spanish MINECOMultiDark CSD2009-00064
Generalitat ValencianaPrometeo/2009/091
Labex grantENIG-MASS
NASA Einstein Postdoctoral FellowshipPF1-120089
Subject Keywords:active galactic nuclei; gamma ray theory; absorption and radiation processes
Issue or Number:11
Record Number:CaltechAUTHORS:20150112-082015973
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Official Citation: Fermi-LAT γ-ray anisotropy and intensity explained by unresolved radio-loud active galactic nuclei Mattia Di Mauro et al JCAP11(2014)021
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53546
Deposited By: Ruth Sustaita
Deposited On:12 Jan 2015 21:04
Last Modified:10 Nov 2021 20:03

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