Gamma Rays From Dark Matter Subhalos Revisited: Refining the Predictions
  and Constraints
  Utilizing data from the ELVIS and Via Lactea-II simulations, we characterize
the local dark matter subhalo population, and use this information to refine
the predictions for the gamma-ray fluxes arising from annihilating dark matter
in this class of objects. We find that the shapes of nearby subhalos are
significantly altered by tidal effects, and are generally not well described by
NFW density profiles, instead prefering power-law profiles with an exponential
cutoff. From the subhalo candidates detected by the Fermi Gamma-Ray Space
Telescope, we place limits on the dark matter annihilation cross section that
are only modestly weaker than those based on observations of dwarf galaxies. We
also calculate the fraction of observable subhalos that are predicted to be
spatially extended at a level potentially discernible to Fermi.
