Search for dark matter annihilation signals from unidentified Fermi-LAT objects with H.E.S.S.

Abstract

Cosmological N-body simulations show that Milky-Way-sized galaxies harbor a population of unmerged dark matter subhalos. These subhalos could shine in gamma rays and be eventually detected in gamma-ray surveys as unidentified sources. We search for very-high-energy (VHE, ≥ 100 GeV) gamma-ray emission using H.E.S.S. observations carried out from a thorough selection of unidentified Fermi-LAT Objects (UFOs) as dark matter subhalo candidates. Provided that the dark matter mass is higher than a few hundred GeV, the emission of the UFOs can be well described by dark matter annihilation models. No significant VHE gamma-ray emission is detected in any UFO dataset nor in their combination. We, therefore, derive constraints on the product of the velocity-weighted annihilation cross-section by the -factor on dark matter models describing the UFO emissions. Upper limits at 95% confidence level are derived on in + − and + − annihilation channels for the TeV dark matter particles. Focusing on thermal WIMPs, strong constraints on the -factors are obtained from H.E.S.S. observations. Adopting model-dependent predictions from cosmological N-body simulations on the -factor distribution function for Milky Way (MW)-sized galaxies, only 0.3 TeV mass dark matter models marginally allow to explain observed UFO emission.

News on Dark Matter from ICRC 2021

“…In fact, the hierarchical formation scenario of the cosmological structures, predicts that a population of dark subhalos should be present in DM halos like that one that hosts our galaxy. At ICRC 2021, the properties and relevance of these substructures for DM searches have been discussed in [4][5][6][7][8][9]. Ref.…”