A study of the gamma-ray Galactic center excess with the Fermi LAT Pass 8 data and limits on dark matter annihilation

by Dmitry Malyshev (University of Erlangen-Nuremberg)

Friday 26 Feb 2016, 12:00 → 13:00 Europe/Madrid

IFAE Seminar room (IFAE)

Dark matter annihilation is expected to be brightest near the Galactic center (GC). Several groups have reported an excess of gamma-ray emission towards the GC that has a peak in spectral energy distribution around a few GeV and it is consistent with a source being approximately spherical in shape. In the talk, I will describe the current observational status of the GC excess and review possible explanations. I will present a recent analysis of the GC excess within the Fermi LAT collaboration with the new Pass 8 data. In this analysis we pay special attention to modeling uncertainties of the foreground gamma-ray emission, additional sources of cosmic rays near the GC, determination of the Fermi bubbles at low latitudes. Although we find that in all models that we have tested the excess emission persists, an astrophysical explanation cannot be excluded at the moment. As an alternative approach to estimate the uncertainty due to diffuse emission modeling we perform a scan of a cusp template along the Galactic plane. We find that the excess emission as a fraction of the background is comparable to the uncertainties found elsewhere in the Galactic plane. We put limits on DM annihilation assuming that DM particles cannot produce a signal that exceeds the uncertainties due to diffuse emission modeling.

Slides GC-Obergurgl-v3.pdf