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Title: Angular power spectrum of the diffuse gamma-ray emission as measured by the Fermi Large Area Telescope and constraints on its dark matter interpretation

The isotropic gamma-ray background arises from the contribution of unresolved sources, including members of confirmed source classes and proposed gamma-ray emitters such as the radiation induced by dark matter annihilation and decay. Clues about the properties of the contributing sources are imprinted in the anisotropy characteristics of the gamma-ray background. We use 81 months of Pass 7 Reprocessed data from the Fermi Large Area Telescope to perform a measurement of the anisotropy angular power spectrum of the gamma-ray background. Here, we analyze energies between 0.5 and 500 GeV, extending the range considered in the previous measurement based on 22 months of data. We also compute, for the first time, the cross-correlation angular power spectrum between different energy bins. The derived angular spectra are compatible with being Poissonian, i.e. constant in multipole. Furthermore, the energy dependence of the anisotropy suggests that the signal is due to two populations of sources, contributing, respectively, below and above ~ 2 GeV . Finally, using data from state-of-the-art numerical simulations to model the dark matter distribution, we constrain the contribution from dark matter annihilation and decay in Galactic and extra-Galactic structures to the measured anisotropy. These constraints are competitive with those that can be derivedmore » from the average intensity of the isotropic gamma-ray background.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [1] ;  [10]
  1. Univ. of Amsterdam (Netherlands)
  2. RWTH Aachen Univ. (Germany). Inst. for Theoretical Particle Physics and Cosmology (TTK)
  3. Univ. of Copenhagen (Denmark). The Niels Bohr Inst.; Univ. of Iceland, Reykjavik (Iceland). Center for Astrophysics and Cosmology
  4. Univ. of Amsterdam (Netherlands); California Inst. of Technology (CalTech), Pasadena, CA (United States)
  5. Oskar Klein Centre for Cosmoparticle Physics, Stockholm (Sweden); Stockholm Univ. (Sweden). Dept. of of Physics
  6. Catholic Univ. of Chile, Santiago (Chile). Inst. of Astrophysics
  7. Max Planck Inst. for Astrophysics, Muchen (Germany); Univ. of Tokyo (Japan). Kavli Inst. for the Physics and Mathematics of the Universe
  8. Univ. of Chicago, IL (United States). Kavli Inst. for Cos; The Ohio State Univ., Columbus, OH (United States). Center for Cosmology and AstroParticle Physics (CCAPP)
  9. Autonomous Univ. of Madrid (Spain). Inst. of Theoretical Physics; Campus of International Excellence UAM+CSIC, Madrid (Spain); Inst. of Astrophysics in Andalucia (IAA0CSIC), Granada (Spain)
  10. National Inst. of Nuclear Physics, Rome (Italy)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; PIIF-GA-2013-62772; PF1-120089; FPA2012-34694; SEV-2012-0249; AYA2014-60641-C2-1-P; PIIF-GA-2013-628997
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 94; Journal Issue: 12; Journal ID: ISSN 2470-0010
American Physical Society (APS)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1335057