Search for dark matter annihilation signatures in H.E.S.S. observations of dwarf spheroidal galaxies

Abstract

Dwarf spheroidal galaxies of the Local Group are close satellites of the Milky Way characterized by a large mass-to-light ratio and are not expected to be the site of nonthermal high-energy gamma-ray emission or intense star formation. Therefore they are among the most promising candidates for indirect dark matter searches. During the last years the High Energy Stereoscopic System (H.E.S.S.) of imaging atmospheric Cherenkov telescopes observed five of these dwarf galaxies for more than 140 hours in total, searching for TeV gamma-ray emission from annihilation of dark matter particles. The new results of the deep exposure of the Sagittarius dwarf spheroidal galaxy, the first observations of the Coma Berenices and Fornax dwarves and the reanalysis of two more dwarf spheroidal galaxies already published by the H.E.S.S. * emrah@physik.hu-berlin.de † Christian.Farnier@fysik.su.se ‡ Giovanni.Lamanna@lapp.in2p3.fr A. ABRAMOWSKI et al.PHYSICAL REVIEW D 90, 112012 (2014) 112012-2Collaboration, Carina and Sculptor, are presented. In the absence of a significant signal new constraints on the annihilation cross section applicable to weakly interacting massive particles (WIMPs) are derived by combining the observations of the five dwarf galaxies. The combined exclusion limit depends on the WIMP mass and the best constraint is reached at 1-2 TeV masses with a cross-section upper bound of ∼ 3.9 × 10 −24 cm 3 s −1 at a 95% confidence level.

Gamma-Ray Dark Matter Searches in Milky Way Satellites—A Comparative Review of Data Analysis Methods and Current Results

“…H.E.S.S also performed early searches on non-confirmed dSphs like Canis Major [59] or even globular clusters [60]. Their most recent searches use state-of-the-art analysis techniques like the one described in Section 3, and are based on observations of Sagittarius (∼90 h), Coma Berenices (∼9 h), Fornax (∼6 h), Carina (∼23 h) and Sculptor (∼13 h) dSphs, where H.E.S.S has searched for both continuum [41] and line-like [44] dark matter spectra. We will concentrate in these two latter works.…”

“…The 95% confidence level upper limits to the cross section of dark matter annihilating into a combination of W + W − and ZZ (left, reprinted figure with permission from reference[41]; copyright (2014) by the American Physical Society) and γγ pairs (right, reprinted figure with permission from reference[44], ©IOP Publishing Ltd and Sissa Medialab; reproduced by permission of IOP Publishing; all rights reserved). Different lines show limits from individual dSphs and from their combination with and without Sagittarius.…”

Aspects of WIMP Dark Matter Searches at Colliders and Other Probes

“…These are satellite galaxies of the Milky Way, with a very low star content and DM dominated. For this reason the signal/background ratio is expected to be large, even if it suffers from large uncertainties [222][223][224][225][226][227][228][229].…”

Wino dark matter in light of the AMS-02 2015 data

“…using four-year data [34]. 4 It should be noted that the constraints on the wino dark matter via monochromatic gamma-ray searches from the galactic center [37] and from the dSphs [38] by the H.E.S.S experiments are less stringent due to large uncertainties of the dark matter profile at the galaxy center (see e.g. Ref.…”