Dark matter (DM) constitutes around a 25% of the Universe, while baryons only
a 4%. DM can be reasonably assumed to be made of particles, and many theories
(Super-symmetry, Universal Extra Dimensions, etc.) predict Weakly Interacting
Massive Particles (WIMPs) as natural DM candidates at the weak scale.
Self-annihilation (or decay) of WIMPs might produce secondary gamma-rays, via
hadronization or as final state radiation. Since its launch in the 2008, the
Large Area Telescope on-board of the Fermi gamma-ray Space Telescope has
detected the largest amount of gamma-rays to date, in the 20MeV 300GeV energy
range, allowing to perform a very sensitive indirect experimental search for DM
(by means of high-energy gamma-rays). DM forms large gravitationally bounded
structures, the halos, which can host entire galaxies, such as the Milky Way.
The DM distribution in the central part of the halos is not experimentally
know, despite a very large density enhancement might be present. As secondary
gamma rays production is very sensitive to WIMP density, a very effective
search can be performed from the regions where the largest density is expected.
Therefore the information provided by the DM halo N-body simulations are
crucial. The largest gamma-ray signal from DM annihilation is expected from the
centre of the Galaxy. In the same region a large gamma-ray background is
produced by bright discrete sources and the cosmic-rays interacting with the
interstellar gas and the photons fields.
Here we report an update of the indirect search for DM from the Galactic
Center (GC).Comment: 6 pages, 2 figures. Invited talk presented at the Workshop "SciNeGHE
2010", September 8-10, 2010, Trieste, Italy. To appear in Il Nuovo Cimento C
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