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Speaker |
Lattanzi, Massimiliano |
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Talk Title |
Enhancement of the dark matter annihilation cross section in cold substructures |
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Abstract |
One of the possible explanations of the positron excess observed by the PAMELA experiment is that it is produced by the annihilation of TeV dark matter particles. However, if this interpretation is correct, the DM annihilation cross section has to be boosted with respect to the primordial value needed to obtain the correct dark matter abundance. A possible way to obtain the boost is via a low-energy enhancement of the cross section due to the presence of a potential between the annihilating particles (Sommerfeld effect). We will show that very large "boost factors" (of order ~ 10^3 or more) can be obtained in this way, and that the main contribution inside the galactic halo comes from the small, cold subhaloes, more than from the smooth halo component. We will discuss the expected diffuse gamma signal and the possibility of constraining the enhancement through the observation of dwarf galaxies like Draco and Sagittarius. |
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