Search for a DM annihilation signal from the Galactic Centre halo with H.E.S.S

The H.E.S.S. experiment, an array of four Imaging Atmospheric Cherenkov Telescopes, observes the Galactic Centre (GC) region in the very high-energy (VHE, E > 100 GeV) γ-ray domain since 2003. The GC is believed to be the region with the highest Dark Matter (DM) density in our Galaxy, thus making it one of the primary targets to look for photons from annihilation or decay of DM particles. The interpretation of the collected H.E.S.S. data with regard to possible DM signals is however complicated by the presence of several astrophysical sources of VHE γ-ray radiation in this region. A new analysis of archival H.E.S.S. data from the GC region avoids such contamination by searching for a DM signal towards a region of projected distance r ~ 45-150 pc from the GC. No residual γ-ray emission is found in the energy range between 300 GeV and 30 TeV, leading to stringent upper limits on the velocity-weighted DM annihilation cross section hs vi. In particular, values for hs vi above 3×10^−25 cm^3 s^−1 are excluded for the Einasto density profile parametrisation.