Local dark matter clumps and the positron excess


E-mail: dtc@astro.ox.ac.uk (DC); silk@astro.ox.ac.uk (JS)


It has been proposed that the excess in cosmic ray positrons at approximately 8 GeV, observed on both flights of the High-Energy Antimatter Telescope (HEAT) balloon experiment, may be associated with the annihilation of dark matter within the Milky Way halo. In this paper, we demonstrate how the self-annihilation of neutralino dark matter within local substructure can account for this excess, and we estimate the annihilation cross-section for several benchmark minimal supersymmetric (MSSM) models. We also demonstrate the changes in the permitted parameter space as the effects of tidal disruption become increasingly severe.