A weighty interpretation of the Galactic Centre excess

International audiencePrevious attempts at explaining the gamma-ray excess near the Galactic Centrehave focussed on dark matter annihilation directly into Standard Modelparticles. This results in a preferred dark matter mass of 30-40 GeV (if theannihilation is into b quarks) or 10 GeV (if it is into leptons). Here we showthat the gamma-ray excess is also consistent with heavier dark matterparticles; in models of secluded dark matter, dark matter with mass up to 76GeV provides a good fit to the data. This occurs if the dark matter firstannihilates to an on-shell particle that subsequently decays to Standard Modelparticles through a portal interaction. This is a generic process that works inmodels with annihilation, semi-annihilation or both. We explicitly demonstratethis in a model of hidden vector dark matter with an SU(2) gauge group in thehidden sector