Dark matter substructure cannot explain properties of the Fermi Galactic
  Centre excess
  An excess of gamma rays has been identified at the centre of the Milky Way,
and annihilation of dark matter has been posited as a potential source. This
hypothesis faces significant challenges: difficulty characterizing
astrophysical backgrounds, the need for a non-trivial adiabatic contraction of
the inner part of the Milky Way's dark matter halo, and recent observations of
photon clustering, which suggest that the majority of the excess is due to
unresolved point sources. Here we point out that the apparent point-like nature
of the emission rules out the dark matter interpretation of the excess
entirely. Attempting to model the emission with dark matter point sources
either worsens the problem with the inner slope, requires an unrealistically
large minihalo fraction toward the Galactic Centre, or overproduces the
observed emission at higher latitudes.
