Distinguishing Dark Matter Annihilation Enhancement Scenarios via Halo Shapes

Understand

Sommerfeld enhancement and Breit-Wigner enhancement of the dark matter annihilation have been proposed to explain the "boost factor" which is suggested by observed cosmic ray excesses.

• Although these two scenarios can provide almost indistinguishable effects on the cosmic ray fluxes, the cross sections of the self-interaction in those enhancement mechanisms are drastically different.
• As a result, we show that they can be distinguished by examining the effects of the self-interaction on the halo shapes.
• In Sommerfeld enhancement models with m_phi<100MeV and m_DM<3TeV, the self-interaction can leave observable imprints in the galactic dynamics, while dark matter is effectively collisionless in Breit-Wigner models.