Constraints on an Annihilation Signal from a Core of Constant Dark Matter Density around the Milky Way Center with H.E.S.S

TL;DR

This study uses H.E.S.S. observations of the Milky Way's center to set new limits on dark matter annihilation, especially considering a constant density core, improving constraints for TeV-scale dark matter particles.

Contribution

It provides the first constraints on dark matter annihilation assuming a constant density core at the Galactic center, independent of cusped density profiles.

Findings

No significant dark matter annihilation signal detected.

Excluded annihilation cross sections above 3×10^{-24} cm^3/s for 1-4 TeV mass range.

Established the strongest constraints for TeV dark matter with a core density profile.

Abstract

An annihilation signal of dark matter is searched for from the central region of the Milky Way. Data acquired in dedicated ON/OFF observations of the Galactic center region with H.E.S.S. are analyzed for this purpose. No significant signal is found in a total of $\sim 9$ h of ON/OFF observations. Upper limits on the velocity averaged cross section, $<\sigma v >$, for the annihilation of dark matter particles with masses in the range of $\sim 300$ GeV to $\sim 10$ TeV are derived. In contrast to previous constraints derived from observations of the Galactic center region, the constraints that are derived here apply also under the assumption of a central core of constant dark matter density around the center of the Galaxy. Values of $<\sigma v >$ that are larger than $3\cdot 10^{-24}\:\mathrm{cm^3/s}$ are excluded for dark matter particles with masses between $\sim 1$ and $\sim 4$ TeV at 95% CL if the radius of the central dark matter density core does not exceed $500$ pc. This is the strongest constraint that is derived on $<\sigma v>$ for annihilating TeV mass dark matter without the assumption of a centrally cusped dark matter density distribution in the search region.