  The presence of an excess gamma-ray signal toward the Galactic center (GC)
has now been well established, and is known as the GC excess. Leading
explanations for the signal include mis-modeling of the Galactic diffuse
emission along the line of sight, an unresolved population of millisecond
pulsars, and/or the annihilation of dark matter (DM). Recently, evidence for
another excess gamma-ray signal has been reported toward the outer halo of M31.
In this work we interpret the excess signals from both the GC and outer halo of
M31 in the framework of DM annihilation, and show that the two spectra are
consistent with a DM origin once J-factors are taken into account. We further
compare the excesses to models of DM annihilation, and determine the
corresponding best-fit parameters. We find good fits to the spectrum both in
two body and four body annihilation modes.

High Energy Astrophysical Phenomena;High Energy Physics - Phenomenology