Fermi-Lat sensitivity to dark matter annihilation in Via Lactea II substructure

We present a study of the ability of the Fermi Gamma-ray Space Telescope to detect dark matter (DM) annihilation signals from the Galactic subhalos predicted by the Via Lactea II N-body simulation. We implement an improved formalism for estimating the boost factor needed to account for the effect of DM clumping on scales below the resolution of the simulation, and we incorporate a detailed Monte Carlo simulation of the response of the Fermi-LAT, including a simulation of its all-sky observing mode integrated over a 10 year mission. We find that for WIMP masses up to about 150 GeV c-2 in standard supersymmetric models with (σv) = 3 × 10-26 cm 3 s-1, a few subhalos could be detectable with >5 standard deviation significance and would likely deviate significantly from the appearance of a point source.