Dark Matter searches towards the WLM dwarf irregular galaxy with H.E.S.S

TL;DR

This paper reports the first gamma-ray observations of the WLM dwarf galaxy with H.E.S.S., aiming to detect dark matter annihilation signals and setting constraints on dark matter particle properties.

Contribution

It presents the first gamma-ray search for dark matter in the WLM dwarf galaxy using H.E.S.S. and provides new limits on dark matter annihilation cross sections.

Findings

No significant gamma-ray excess detected.

Set new upper limits on dark matter annihilation cross section.

First imaging atmospheric Cherenkov observations of WLM galaxy.

Abstract

In the indirect dark matter (DM) detection framework, the DM particles would produce some signals by self-annihilating and creating standard model products such as gamma rays, which might be detected by ground-based telescopes. Dwarf irregular galaxies represent promising targets for the search for DM as they are assumed to be dark matter dominated systems at all radii. These dwarf irregular galaxies are rotationally supported with relatively simple kinematics which lead to small uncertainties on their dark matter distribution profiles. In 2018, the H.E.S.S. telescopes observed the irregular dwarf galaxy Wolf-Lundmark-Melotte (WLM) for a live time of 19 hours. These observations are the very first ones made by an imaging atmospheric Cherenkov telescope toward this kind of object. We search for a DM signal looking for an excess of gamma rays over the background in the direction of the WLM galaxy. We present the first results obtained on the velocity weighted cross section for DM self-annihilation as a function of DM particle mass.