| Abstract: | The inner region of the Milky Way halo harbors a large amount of dark matter
(DM). Given its proximity, it is one of the most promising targets to look for
DM. We report on a search for the annihilations of DM particles using
$gamma$-ray observations towards the inner 300 parsecs of the Milky Way, with
the H.E.S.S. array of ground-based Cherenkov telescopes. The analysis is based
on a 2D maximum likelihood method using Galactic center (GC) data accumulated
by H.E.S.S. over the last 10 years (2004-2014), and does not show any
significant $gamma$-ray signal above background. Assuming Einasto and
Navarro-Frenk-White DM density profiles at the GC, we derive upper limits on
the annihilation cross section $langle sigma v
angle$. These constraints are
the strongest obtained so far in the TeV DM mass range and improve upon
previous limits by a factor 5. For the Einasto profile, the constraints reach
$langle sigma v
angle$ values of $
m 6 imes10^{-26} cm^3s^{-1}$ in the
$W^+W^-$ channel for a DM particle mass of 1.5 TeV, and $
m 2 imes10^{-26}
cm^3s^{-1}$ in the $ au^+ au^-$ channel for 1 TeV mass. For the first time,
ground-based $gamma$-ray observations have reached sufficient sensitivity to
probe $langle sigma v
angle$ values expected from the thermal relic density
for TeV DM particles. |
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