Enrico Borriello, Luca Maccione, Alessandro Cuoco
We study the dipole anisotropy in the arrival directions of high energy CR
electrons and positrons (CRE) of Dark Matter (DM) origin. We show that this
quantity is very weakly model dependent and offers a viable criterion to
discriminate among CRE from DM or from local discrete sources, like e.g.
pulsars. In particular, we find that the maximum anisotropy which DM can
provide is to a very good approximation a universal quantity and, as a
consequence, if a larger anisotropy is detected, this would constitute a strong
evidence for the presence of astrophysical local discrete CRE sources, whose
anisotropy, instead, can be naturally larger than the DM upper limit. We
further find that the main source of anisotropy from DM is given by the
fluctuation in the number density of DM sub-structures in the vicinity of the
observer and we thus devote special attention to the study of the variance in
the sub-structures realization implementing a dedicated Montecarlo simulation.
Such scenarios will be probed in the next years by Fermi-LAT, providing new
hints, or constraints, about the nature of DM.
View original:
http://arxiv.org/abs/1012.0041
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