Challenges in Explaining the Galactic Center Gamma-Ray Excess with
  Millisecond Pulsars
  Millisecond pulsars have been discussed as a possible source of the gamma-ray
excess observed from the region surrounding the Galactic Center. With this in
mind, we use the observed population of bright low-mass X-ray binaries to
estimate the number of millisecond pulsars in the Inner Galaxy. This
calculation suggests that only ~1-5% of the excess is produced by millisecond
pulsars. We also use the luminosity function derived from local measurements of
millisecond pulsars, along with the number of point sources resolved by Fermi,
to calculate an upper limit for the diffuse emission from such a population.
While this limit is compatible with the millisecond pulsar population implied
by the number of low-mass X-ray binaries, it strongly excludes the possibility
that most of the excess originates from such objects.
