Maneenate Wechakama, Yago Ascasibar
We investigate the production of electrons and positrons in the Milky Way within the context of dark matter annihilation. Upper limits on the relevant cross-section are obtained by combining observational data at different wavelengths (from Haslam, WMAP, and Fermi all-sky intensity maps) with recent measurements of the electron and positron spectra in the solar neighbourhood by PAMELA, Fermi, and HESS. We consider synchrotron emission in the radio and microwave bands, as well as inverse Compton scattering and final-state radiation at gamma-ray energies. For most values of the model parameters, the tightest constraints are imposed by the local positron spectrum and the final-state radiation from the central regions of the Galaxy. According to our results, the dark matter annihilation cross-section into electron-positron pairs should not be higher than the canonical value for a thermal relic if the mass of the dark matter candidate is smaller than a few GeV. In addition, we also derive a stringent upper limit on the inner logarithmic slope (alpha) of the density profile of the Milky Way dark matter halo (alpha < 1.3 if m_dm < 100 GeV and alpha < 1.8 if m_dm < 10TeV) assuming that cross-section = 3 x 10^(-26) cm^3 s^(-1).
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http://arxiv.org/abs/1212.2583
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