95.35.+d, 95.85.Pw, Dark matter, gamma-ray, Astrophysics - High Energy Astrophysical Phenomena
Beschreibung:
Gamma-ray line signatures can be expected in the very-high-energy (Eγ>100 GeV) domain due to self-annihilation or decay of dark matter (DM) particles in space. Such a signal would be readily distinguishable from astrophysical γ-ray sources that in most cases produce continuous spectra that span over several orders of magnitude in energy. Using data collected with the H.E.S.S. γ-ray instrument, upper limits on linelike emission are obtained in the energy range between ∼500 GeV and ∼25 TeV for the central part of the Milky Way halo and for extragalactic observations, complementing recent limits obtained with the Fermi-LAT instrument at lower energies. No statistically significant signal could be found. For monochromatic γ-ray line emission, flux limits of (2×10−7–2×10−5) m−2 s−1 sr−1 and (1×10−8–2×10−6) m−2 s−1 sr−1 are obtained for the central part of the Milky Way halo and extragalactic observations, respectively. For a DM particle mass of 1 TeV, limits on the velocity-averaged DM annihilation cross section ⟨σv⟩χχ→γγ reach ∼10−27 cm3 s−1, based on the Einasto parametrization of the Galactic DM halo density profile.