Dark Matter interpretations of the image excesses after FERMI Original Research Article

The cosmic-ray excess observed by PAMELA in the positron fraction and by FERMI and HESS in image can be interpreted in terms of DM annihilations or decays into leptonic final states. Final states into τʹs or 4μ give the best-fit to the excess. However, in the annihilation scenario, they are incompatible with photon and neutrino constraints, unless DM has a quasi-constant density profile. Final states involving eʹs are less constrained but poorly fit the excess, unless hidden sector radiation makes their energy spectrum smoother, allowing a fit to all the data with a combination of leptonic modes. In general, DM lighter than about a TeV cannot fit the excesses, so PAMELA should find a greater positron fraction at higher energies. The DM interpretation can be tested by FERMI γ observations above 10 GeV: if the image excess is everywhere in the DM halo, Inverse Compton scattering on ambient light produces a well-predicted γ excess that FERMI should soon detect.