Search for dark matter annihilation towards the inner Milky Way halo with the H.E.S.S. Inner Galaxy Survey

Abstract

The presence of dark matter (DM) is suggested by a wealth of astrophysical and cosmological measurements. However, its underlying nature is yet unknown. Among the most promising candidates are weakly interacting massive particles (WIMPs): particles with mass and coupling strength at the electroweak scale and thermally-produced in the early universe have a present relic density consistent with that observed today. WIMP self-annihilation would produce Standard Model particles including gamma-rays, which have been long-time recognized as a prime messenger to indirectly detect dark matter signals. The centre of the Milky Way is predicted as the brightest source of DM annihilations. The H.E.S.S. collaboration is currently performing a survey of the inner region of the Milky Way, the Inner Galaxy Survey (IGS), intended to achieve the best sensitivity to faint and diffuse emissions in a region of several degrees around the Galactic Centre. We analyzed 2014-2020 observations taken with the five-telescope array to search for a DM annihilation signal. With the current dataset of about 550 hours, we found no significant excess and therefore derived strong constraints on the velocity-weighted annihilation cross-section. TeV thermal WIMPs can be probed in different annihilation channels.

News on Dark Matter from ICRC 2021

“…2. For the same reason, the DM distribution plays a crucial role also in the limits obtained in [11].…”

“…The origin and properties of the excess have been investigated extensively in the literature, see [13][14][15] and references therein. The most discussed explanations are in terms of DM annihilations, or [11]. Bottom: Upper limits on the DM annihilation cross section into γγ from a search of spectral lines performed by MAGIC.…”

“…Searches of DM signals from the galactic center region have been presented by the MAGIC [12] and H.E.S.S. [11] collaborations. Ref.…”

“…Ref. [11] presented an analysis based on 546 hours of observations performed between 2014 and 2020. The region of interest for the search extends up to 2.9 degrees from the galactic center.…”

“…Figure 2: Top: Upper limits on the DM annihilation cross section into W + W − from a DM search at the galactic center region with H.E.S.S. Taken from[11]. Bottom: Upper limits on the DM annihilation cross section into γγ from a search of spectral lines performed by MAGIC.…”