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Title: NEW LIMITS ON GAMMA-RAY EMISSION FROM GALAXY CLUSTERS

Galaxy clusters are predicted to produce γ-rays through cosmic ray interactions and/or dark matter annihilation, potentially detectable by the Fermi Large Area Telescope (Fermi-LAT). We present a new, independent stacking analysis of Fermi-LAT photon count maps using the 78 richest nearby clusters (z < 0.12) from the Two Micron All Sky Survey cluster catalog. We obtain the lowest limit on the photon flux to date, 2.3 × 10{sup –11} photons cm{sup –2} s{sup –1} (95% confidence) per cluster in the 0.8-100 GeV band, which corresponds to a luminosity limit of 3.5 × 10{sup 44} photons s{sup –1}. We also constrain the emission limits in a range of narrower energy bands. Scaling to recent cosmic ray acceleration and γ-ray emission models, we find that cosmic rays represent a negligible contribution to the intra-cluster energy density and gas pressure.
Authors:
;  [1] ;  [2]
  1. Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK, 73019 (United States)
  2. Department of Astronomy and the Center for Cosmology and Astroparticle Physics, Ohio State University, Columbus, OH 43210 (United States)
Publication Date:
OSTI Identifier:
22364491
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 795; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ANNIHILATION; COSMIC PHOTONS; COSMIC RADIATION; ENERGY DENSITY; GALAXY CLUSTERS; GAMMA RADIATION; GEV RANGE; LUMINOSITY; NONLUMINOUS MATTER; PHOTON EMISSION; POTENTIALS; TELESCOPES