Decaying Dark Matter in Light of the PAMELA and Fermi LAT Data

Abstract

A series of experiments measuring high-energy cosmic rays have recently reported strong indications for the existence of an excess of high-energy electrons and positrons. If interpreted in terms of the decay of dark matter particles, the PAMELA measurements of the positron fraction and the Fermi LAT measurements of the total electron-plus-positron flux restrict the possible decaying dark matter scenarios to a few cases. Analyzing different decay channels in a model-independent manner, and adopting a conventional diffusive reacceleration model for the background fluxes of electrons and positrons, we identify some promising scenarios of dark matter decay and calculate the predictions for the diffuse extragalactic gamma-ray flux, including the contributions from inverse Compton scattering with the interstellar radiation field.