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Title: Search for gamma-ray lines towards galaxy clusters with the Fermi-LAT

We report on a search for monochromatic γ-ray features in the spectra of galaxy clusters observed by the Fermi Large Area Telescope. Galaxy clusters are the largest structures in the Universe that are bound by dark matter (DM), making them an important testing ground for possible selfinteractions or decays of the DM particles. Monochromatic γ-ray lines provide a unique signature due to the absence of astrophysical backgrounds and are as such considered a smoking-gun signature for new physics. An unbinned joint likelihood analysis of the sixteen most promising clusters using five years of data at energies between 10 and 400 GeV revealed no significant features. For the case of self-annihilation, we set upper limits on the monochromatic velocity-averaged interaction cross section. These limits are compatible with those obtained from observations of the Galactic Center, albeit weaker due to the larger distance to the studied clusters.
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [3]
  1. The Oskar Klein Centre for Cosmoparticle Physics (Sweden); Stockholm Univ. (Sweden). Dept. of Physics
  2. Georg-August Univ. Gottingen (Germany)
  3. Univ. of California, Santa Cruz, CA (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Cosmology and Astroparticle Physics
Additional Journal Information:
Journal Volume: 2016; Journal Issue: 02; Journal ID: ISSN 1475-7516
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE; National Aeronautics and Space Administration (NASA); European Union (EU); Japan Aerospace Exploration Agency (JAXA); Swedish Research Council (SRC)
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; dark matter experiments; galaxy clusters; gamma ray experiments
OSTI Identifier: