  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.
