Andi Hektor, Martti Raidal, Elmo Tempel
We search for spectral features in Fermi-LAT gamma-rays coming from regions corresponding to six most massive nearby galaxy clusters. We observe a sharp peak at photon energy 130 GeV over the diffuse power-law background with statistical significance up to 3.2\sigma, confirming independently earlier claims of the 130 GeV gamma-ray line from the Galactic centre. Interpreting this result as a signal of dark matter annihilations to monochromatic photons in galaxy cluster haloes, and fixing the annihilation cross section from Galactic centre data, we determine the annihilation boost factor due to dark matter subhaloes to be of order 1000, in agreement with theoretical expectations for the galaxy clusters.
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http://arxiv.org/abs/1207.4466
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