Search for a Dark Matter Annihilation Signal from the Galactic Center Halo with H.E.S.S.

Abstract

A search for a very-high-energy (VHE; $\ensuremath{\ge}100\text{ }\text{ }\mathrm{GeV}$) $\ensuremath{\gamma}$-ray signal from self-annihilating particle dark matter (DM) is performed towards a region of projected distance $r\ensuremath{\sim}45--150\text{ }\text{ }\mathrm{pc}$ from the Galactic center. The background-subtracted $\ensuremath{\gamma}$-ray spectrum measured with the High Energy Stereoscopic System (H.E.S.S.) $\ensuremath{\gamma}$-ray instrument in the energy range between 300 GeV and 30 TeV shows no hint of a residual $\ensuremath{\gamma}$-ray flux. Assuming conventional Navarro-Frenk-White and Einasto density profiles, limits are derived on the velocity-weighted annihilation cross section $⟨\ensuremath{\sigma}v⟩$ as a function of the DM particle mass. These are among the best reported so far for this energy range and in particular differ only little between the chosen density profile parametrizations. In particular, for the DM particle mass of $\ensuremath{\sim}1\text{ }\text{ }\mathrm{TeV}$, values for $⟨\ensuremath{\sigma}v⟩$ above $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}25}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ are excluded for the Einasto density profile.