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

2 Sep 2021, 17:10
Talk in parallel session Dark Matter and its detection Discussion Panel Dark Matter 9


Alessandro Montanari (CEA Saclay / Irfu-DPhP - Université Paris Saclay)


Milky Way-sized galaxies harbor a population of unmerged dark matter subhalos, as shown from cosmological N-body simulations. These subhalos could shine in gamma-rays and be eventually detected as unidentified sources in gamma-ray surveys. From a thorough selection of unidentified Fermi-LAT Objects (UFOs), we observe four UFOs with H.E.S.S. and we search for very high-energy (VHE, E ≥ 100 GeV) gamma-ray emission. Considering dark matter masses above a few hundred GeV, the observed UFOs could be identified as dark matter subhalos, given their hard gamma-ray spectra in the few-ten-to-hundred GeV energy range. Since no significant very-high-energy gamma-ray emission is detected in any of the four UFOs dataset nor in the combined one, we derive constraints on the product of the velocity-weighted annihilation cross-section <$\sigma$ v> by the J-factor for the dark matter models. We derive 95% CL upper limits on <$\sigma$ v>J in W$^+$W$^-$ and $\tau^+$$\tau^-$ annihilation channels for the TeV dark matter particles. Considering thermal WIMPs, we derive constraints on the J-factors from the H.E.S.S. observations. Assuming model-dependent predictions from cosmological N-body simulations on the J-factor distribution for Milky Way-sized galaxies, the dark matter models with masses greater than 0.3 TeV for the UFO emissions can be ruled out at high confidence level.

Reference to paper (DOI or arXiv)

Primary authors

Alessandro Montanari (CEA Saclay / Irfu-DPhP - Université Paris Saclay) Dr. Emmanuel Moulin (CEA Saclay / Irfu-DPhP - Université Paris Saclay) Dr. Dorit Glawion (ECAP, FAU, Erlangen Centre for Astroparticle Physics ) Dr. Denys Malyshev, for the H.E.S.S. collaboration ((IAAT) Eberhard Karls Universität Tübingen: Tubingen)

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