Overcoming Gamma Ray Constraints with Annihilating Dark Matter in Milky Way Subhalos

Understand

We reconsider Sommerfeld-enhanced annihilation of dark matter (DM) into leptons to explain PAMELA and Fermi electron and positron observations, in light of possible new effects from substructure.

• There is strong tension between getting a large enough lepton signal while respecting constraints on the fluxes of associated gamma rays.
• We first show that these constraints become significantly more stringent than in previous studies when the contributions from background e^+ e^- are taken into account, so much so that even cored DM density profiles are ruled out.
• We then show how DM annihilations within subhalos can get around these constraints.