Decaying vs. annihilating dark matter in light of a tentative gamma-ray line

Abstract

Recently reported tentative evidence for a gamma-ray line in the Fermi-LATdata is of great potential interest for identifying the nature of dark matter.We compare the implications for decaying and annihilating dark matter taking the constraints from continuum gamma-rays, antiprotonflux and morphology of the excess into account. We find that higgsinoand wino dark matter are excluded, also for nonthermal production.Generically, the continuum gamma-ray flux severely constrains annihilatingdark matter. Consistency of decaying dark matter with thespatial distribution of the Fermi-LAT excess would require an enhancementof the dark matter density near the Galactic center.