H.E.S.S. limits on line-like dark matter signatures in the 100 GeV to 2 TeV energy range close to the Galactic Centre

TL;DR

This study used H.E.S.S. data to search for line-like dark matter signals near the Galactic Centre, extending energy coverage down to 100 GeV, but found no significant signals and set upper limits on dark matter annihilation.

Contribution

Developed an improved unbinned likelihood analysis and extended the energy range of dark matter line searches with H.E.S.S. data, providing new constraints.

Findings

Ruled out a 130 GeV line at 95% CL in the observed region.

No significant dark matter signal detected between 100 GeV and 2 TeV.

Set upper limits on gamma-ray flux and annihilation cross-section.

Abstract

A search for dark matter line-like signals was performed in the vicinity of the Galactic Centre by the H.E.S.S. experiment on observational data taken in 2014. An unbinned likelihood analysis was developed to improve the sensitivity to line-like signals. The upgraded analysis along with newer data extend the energy coverage of the previous measurement down to 100 GeV. The 18 h of data collected with the H.E.S.S. array allow one to rule out at 95% CL the presence of a 130 GeV line (at $l = -1.5^{\circ}, b = 0^{\circ}$ and for a dark matter profile centered at this location) previously reported in Fermi-LAT data. This new analysis overlaps significantly in energy with previous Fermi-LAT and H.E.S.S. results. No significant excess associated with dark matter annihilations was found in the energy range 100 GeV to 2 TeV and upper limits on the gamma-ray flux and the velocity weighted annihilation cross-section are derived adopting an Einasto dark matter halo profile. Expected limits for present and future large statistics H.E.S.S. observations are also given.