Limits on dark matter annihilation cross sections to gamma-ray lines with subhalo distributions inN-body simulations and Fermi LAT data

Abstract

In this work, we simulate a set of realizations of local volume dark matter subhalo population based on the distributions and relations derived from Via Lactea II N-body simulation. We calculate the J-factors of these subhalos, and find that the low mass subhalos contribute a lot to the total J-factors. Combining with 91 months of the Fermi LAT observation, we constrain on the cross section of dark matter annihilating directly to two gamma rays. This is the first work combining numerical simulation results and Fermi LAT observations to constrain dark matter cross section to gamma-ray line with subhalo population. Though the constraints derived from subhalo population are weaker than those from Fermi LAT observation of the Galactic center, they are supports of and complementary to these other results.