Abstract
We derive constraints on parameters of generic dark matter
candidates by comparing theoretical predictions with the gamma-ray
emission observed by the Fermi-LAT from the region around
the Galactic Center. Our analysis is conservative since it simply
requires that the expected dark matter signal does not exceed the
observed emission. The constraints obtained in the likely case that
the collapse of baryons to the Galactic Center is accompanied by the
contraction of the dark matter are strong. In particular, we find
that for b
and τ+τ− or W+W− dark matter
annihilation channels, the upper limits on the annihilation cross
section imply that the thermal cross section is excluded for a
Weakly Interacting Massive Particle (WIMP) mass smaller than about
700 and 500 GeV, respectively. For the μ+μ− channel, where
the effect of the inverse Compton scattering is important, depending
on models of the Galactic magnetic field the exclusion of the
thermal cross-section is for a WIMP mass smaller than about 150 to
400 GeV. The upper limits on the annihilation cross section of dark
matter particles obtained are two orders of magnitude stronger than
without contraction. In the latter case our results are compatible
with the upper limits from the Galactic halo analysis reported by
the Fermi-LAT collaboration for the case in which the same
conservative approach without modeling of the astrophysical
background is employed.