Evaluating the Gamma-Ray Evidence for Self-Annihilating Dark Matter from the Virgo Cluster

Abstract

Based on three years of Fermi Large Area Telescope (LAT) gamma-ray data of the Virgo cluster, evidence for an extended emission associated with dark matter pair annihilation in the b b-bar channel has been reported by Han et al. [1]. After an in depth spatial and temporal analysis, we argue that the tentative evidence for a gamma-ray excess from the Virgo cluster is mainly due to the appearance of a population of previously unresolved gamma-ray point sources in the region of interest. These point sources are not part of the LAT second source catalogue (2FGL), but are found to be above the standard detection significance threshold when three or more years of LAT data is included.

6 pages, 5 figures, minor changes, conclusions unchanged, matches final version to appear in PRD

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• Constraining Extended Gamma-ray Emission from Galaxy Clusters
• Search for extended gamma-ray emission from the Virgo galaxy cluster with Fermi-LAT
• WIMP searches with gamma rays in the Fermi era: challenges, methods and results
• Constraints on Dark Matter Annihilation in Clusters of Galaxies from Diffuse Radio Emission
• Indirect Detection of Dark Matter with gamma rays
• Neutrinos in IceCube/KM3NeT as probes of Dark Matter Substructures in Galaxy Clusters
• Rapid Gamma-ray variability of NGC 1275
• Strong Optimized Conservative Fermi-LAT Constraints on Dark Matter Models from the Inclusive Photon Spectrum
• TeV Dark Matter Searches in the Extragalactic Gamma-Ray Sky
• Very High Energy gamma-ray emission from RBS 0970
• Very high energy $\gamma$-ray emission from RBS 0679