Fermi Gamma-ray Space Telescope

The inner Milky Way's extended gamma-ray excess: evidence of self-annihilating dark matter?

Anna Kwa
Kevork Abazajian, Nicolas Canac, Shunsaku Horiuchi, Manoj Kaplinghat

Abstract:

We present novel findings from our study of the reported gamma-ray excess in the inner Milky Way region. Recent papers claim a robust detection of excess emission extending as far as ~10 degrees from the galactic center, whose spatial morphology and spectrum are both consistent with an origin from WIMP dark matter annihilation. We search for such an excess out to latitudes of ~20 degrees and test whether or not it is roughly spherically symmetric, as would be expected in the case of a dark matter origin. We make novel use of the composite likelihood analysis tools to aid in our modelling of the diffuse background and Fermi bubbles. Within the innermost 7x7 degree region, we consider the effects on the extracted gamma-ray excess when additional extended astrophysical sources are included in the background model.