Search for a Dark Matter annihilation signal from the Galactic Center halo with H.E.S.S

TL;DR

This study used H.E.S.S. gamma-ray data to search for dark matter annihilation signals near the Galactic Center, setting new limits on the annihilation cross section for particles around 1 TeV, with no detected excess.

Contribution

First to analyze H.E.S.S. data for dark matter signals in the 45-150 pc Galactic Center region, deriving competitive limits on annihilation cross sections for TeV-scale dark matter.

Findings

No gamma-ray excess detected from the region.

Limits on <σv> exclude values above 3×10^(-25) cm^3 s^(-1) for 1 TeV mass.

Results are less sensitive to density profile assumptions than other gamma-ray observations.

Abstract

A search for a very-high-energy (VHE; >= 100 GeV) gamma-ray signal from self-annihilating particle Dark Matter (DM) is performed towards a region of projected distance r ~ 45-150 pc from the Galactic Center. The background-subtracted gamma-ray spectrum measured with the High Energy Stereoscopic System (H.E.S.S.) gamma-ray instrument in the energy range between 300 GeV and 30 TeV shows no hint of a residual gamma-ray flux. Assuming conventional Navarro-Frenk-White (NFW) and Einasto density profiles, limits are derived on the velocity-weighted annihilation cross section < \sigma v> as a function of the DM particle mass. These are among the best reported so far for this energy range. In particular, for the DM particle mass of ~1 TeV, values for <\sigma v> above 3 * 10^(-25) cm^3 s^(-1) are excluded for the Einasto density profile. The limits derived here differ much less for the chosen density profile parametrizations, as opposed to limits from gamma-ray observations of dwarf galaxies or the very center of the Milky Way, where the discrepancy is significantly larger.