Constraining Dark Matter in Galactic Substructure
  Detecting the dark matter annihilation signal from Galactic substructure, or
subhalos, is an important challenge for high-energy gamma-ray experiments. In
this paper we discuss detection prospects by combining two different aspects of
the gamma-ray signal: the angular distribution and the photon counts
probability distribution function (PDF). The true PDF from subhalos has been
shown recently (by Lee et al.) to deviate from Poisson; we extend this analysis
and derive the signal PDF from a detailed Lambda-CDM-based model for the
properties of subhalos. We combine our PDF with a model for Galactic and
extra-Galactic diffuse gamma-ray emission to obtain an estimator and projected
error on dark matter particle properties (mass and annihilation cross section)
using the Fermi Gamma-Ray Space Telescope. We compare the estimator obtained
from the true PDF to that obtained from the simpler Poisson analysis. We find
that, although both estimators are unbaised in the presence of backgrounds, the
error on dark matter properties derived from the true PDF is ~50% smaller than
when utilizing the Poisson-based analysis.
