Mingxing Luo, Liucheng Wang, Guohuai Zhu
We propose a novel method to directly determine the dark matter (DM) induced
electron/positron spectrum at the source from experimental measurements at the
earth, without reference to specific particle physics models. The DM induced
gamma rays emitted via inverse Compton scattering are obtained in a model
independent way. However the results depend on the choice of the astrophysical
electron/positron background, which is not reliably known. Nevertheless, we
calculate, as an illustration, the fluxes of gamma rays from the Fornax cluster
in the decaying DM scenario with various astrophysical backgrounds. The
predictions turn out to be either in disagreement with or only marginally below
the upper limits measured recently by the Fermi-LAT Collaboration. This
provides a strong constraint on decaying DM scenario as the gamma rays may be
produced in other processes besides inverse Compton scattering, such as the
bremsstrahlung and neutral pion decays. In addition, these gamma rays in the
GeV range are shown to be almost independent of choices of cosmic ray
propagation model and of DM density profile.
View original:
http://arxiv.org/abs/1107.3024
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