A Robust Method for Treating Astrophysical Mismodeling in Dark Matter
  Annihilation Searches of Dwarf Spheroidal Galaxies
  Fermi-LAT observations have strongly constrained dark matter annihilation
through the joint-likelihood analysis of dwarf spheroidal galaxies (dSphs).
These constraints are expected to be robust because dSphs have measurable dark
matter content and produce negligible astrophysical emission. However, each
dSph is dim, with a predicted flux that typically falls below the accuracy of
the background model. We show that this significantly diminishes the
reliability of previous joint-likelihood algorithms, and develop an improved
analysis that directly accounts for the effect of background mismodeling. This
method produces more robust limits and detections of dark matter in both real
and mock data. We calculate improved limits on the dark matter annihilation
cross-section, which differ by nearly a factor of two from previous analyses -
despite examining identical data.
