Gamma-rays From Neutralino Annihilation in Milky Way Substructure: What Can We Learn?

We estimate the probability of detecting gamma-rays from the annihilation of neutralino dark matter in the substructure of the Milky Way. We characterize substructure statistically based on Monte Carlo realizations of the formation of a Milky Way-like halo using semi-analytic methods that have been calibrated against N-body simulations. We find that it may be possible for the upcoming GLAST and VERITAS experiments, working in concert, to detect gamma-rays from dark matter substructure if $\Mchi \lsim 100 \GeV$, while for $\Mchi \gsim 500 \GeV$ such a detection seems unlikely. We investigate the effects of the underlying cosmological model and find that the probability of detection is sensitive to the primordial power spectrum of density fluctuations on small (galactic and sub-galactic) scales. We conclude that the lack of such a detection reveals little about the supersymmetric parameter space due to the uncertainties associated with the properties of substructure and cosmological parameters.