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

TL;DR

This study reanalyzes gamma-ray data from the Virgo cluster, suggesting that previously reported evidence for dark matter annihilation signals is likely due to unresolved point sources rather than dark matter itself.

Contribution

The paper provides a detailed spatial and temporal analysis showing that gamma-ray excesses are attributable to unresolved point sources, challenging prior dark matter interpretations.

Findings

Gamma-ray excess is due to unresolved point sources.

No significant evidence for dark matter annihilation in Virgo.

Extended emission is explained by point source population.

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.