Constraining dark matter microphysics with the annihilation signal from subhalos

In the cold dark matter scenario, galactic halos are populated with a large number of smaller subhalos. Previous work has shown that annihilations in subhalos can generate distinctive, non-Poisson signal gamma-ray photon counts probability distribution function (PDF). Here we show PDF also carries information about velocity dependence annihilation cross section. After calculating assuming $s$-wave and Sommerfeld-enhanced annihilation, perform mock data analysis to illustrate how current future observations constrain microphysics annihilation. We find that, Fermi data, section roughly at limit bounds from dwarf spheroidal galaxies, one potentially distinguish non-Poissonian fluctuations expected Poisson sources, as well models an incorrect velocity-dependence. explore robust these results assumptions modeling astrophysical backgrounds. point out four-parameter degeneracy between minimum subhalo mass, power law index mass function, normalization signal. This be broken priors N-body simulations or observational constraints on function.