Hunting for Dark Matter in Anisotropies of the Gamma-ray Sky: Predictions and Observational Results from Fermi-LAT
Tuesday 14 February 2017
to 14:30 at
Can we use the Fermi gamma-ray satellite like WMAP? In 2006, we proposed to use anisotropies in the distribution of photons in the sky in gamma-ray energies (not the cosmic microwave background!) as a smoking-gun signature of annihilation of dark matter particles in the universe. The idea is simple: since dark matter traces the large-scale structure of the universe, the emission from dark matter must appear anisotropic in the sky, and its spatial pattern is predictable. The use of anisotropy (especially the power spectrum) was new to the gamma-ray community, so we teamed up with the Fermi-LAT team to look for this signature. Here, we report on the first detection of anisotropy in the diffuse gamma-ray background measured by Fermi-LAT. We find that the detected signal is very likely due to unresolved blazers. Subtracting this signal, we place a stringent upper limit on the residual anisotropy signal, which would put constraints on dark matter properties. We then report on the latest results from 81 months of the Fermi-LAT data.