New Limits On Gamma-Ray Emission From Galaxy Clusters

Abstract

Galaxy clusters are predicted to produce gamma-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 (2MASS) cluster catalog. We obtain the lowest limit on the photon flux to date, 2.3e-11 ph/s/cm^2 (95% confidence) per cluster in the 0.8-100 GeV band, which corresponds to a luminosity limit of 3.5e44 ph/s. We also constrain the emission limits in a range of narrower energy bands. Scaling to recent cosmic ray acceleration and gamma-ray emission models, we find that cosmic rays represent a negligible contribution to the intra-cluster energy density and gas pressure.

5 pages, 3 figures, 2 tables, Accepted by ApJ Letters

References in corpus (2)

• Constraining Extended Gamma-ray Emission from Galaxy Clusters
• Gamma Rays from Clusters and Groups of Galaxies: Cosmic Rays versus Dark Matter

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• High-energy gamma-ray and neutrino backgrounds from clusters of galaxies and radio constraints
• Shocks and non-thermal particles in clusters of galaxies
• Cross-correlating the gamma-ray sky with catalogs of galaxy clusters
• On the Challenges of Cosmic-Ray Proton Shock Acceleration in the Intracluster Medium
• Neutrino Constrains to the Diffuse Gamma-Ray Emission from Accretion Shocks
• RXTE Observation of the Non-thermal Emission from the Early Stage Merger in Abell 1750