Constraining Extended Gamma-ray Emission from Galaxy Clusters

Understand

Cold dark matter models predict the existence of a large number of substructures within dark matter halos.

• If the cold dark matter consists of weakly interacting massive particles, their annihilation within these substructures could lead to diffuse GeV emission that would dominate over the annihilation signal of the host halo.
• In this work we search for GeV emission from three nearby galaxy clusters: Coma, Virgo and Fornax.
• We first remove known extragalactic and galactic diffuse gamma-ray backgrounds and point sources from the Fermi 2-year catalog and find a significant residual diffuse emission in all three clusters.