Dark matter search in the inner galactic center halo with H.E.S.S

Abstract: The presence of dark matter in the universe is nowadays supported by a substantial set of astronomical and cosmological observations. A large amount of dark matter is expected in the Galactic Center (GC) region. Thanks also to its proximity, it is one of the best targets to look for dark matter particle self-annihilation into very high energy gamma-rays. We perform a search for annihilating dark matter in the central 300 parsecs around the GC with the H.E.S.S. array of ground-based Cherenkov telescopes. Using the full H.E.S.S.- I dataset (2004-2014) of GC observations, new constraints are derived on the velocity-weighted annihilation cross section $\langle \sigma v \rangle$ with a 2D likelihood method using spectral and spatial morphologies of the DM signal compared to background. These constraints are the strongest obtained so far in the TeV mass range and improve the previous constraints by a factor of 5. Considering an Einasto profile, the constraints reach $\langle \sigma v \rangle$ values of $6\times 10^{-26}$cm$^{3}$s$^{-1}$ for a DM particle mass of 1.5 TeV annihilation into W$^+$W$^-$ pairs. In the $\tau^+\tau^-$ channel, the constraints probe the natural scale for thermal relic cross section for DM particles of masses between 400 GeV and 2 TeV.