The Contribution of Cosmic Rays Interacting With Molecular Clouds to the
  Galactic Center Gamma-Ray Excess
  The Fermi-LAT data appear to have an excess of gamma rays from the inner 150
pc of the Galactic Center. The main explanations proposed for this are: an
unresolved population of millisecond pulsars (MSPs), dark matter (DM)
annihilation, and nonthermal bremsstrahlung produced by a population of
electrons interacting with neutral gas in molecular clouds. The first two
options have spatial templates well fitted by the square of a generalized
Navarro-Frenk-White (NFW) profile with inner slope $\gamma=1.2$. We model the
third option with a 20-cm continuum emission Galactic Ridge template. A
template based on the HESS residuals is shown to give similar results. The
gamma-ray excess is found to be best fit by a combination of the generalized
NFW squared template and a Galactic Ridge template. We also find the spectra of
each template is not significantly affected in the combined fit and is
consistent with previous single template fits. That is the generalized NFW
squared spectrum can be fit by either of order 1000 unresolved MSPs or DM with
mass around 30 GeV, a thermal cross section, and mainly annihilating to $b
\bar{b}$ quarks. While the Galactic Ridge continues to have a spectrum
consistent with a population of nonthermal electrons whose spectrum also
provides a good fit to synchrotron emission measurements. We also show that the
current DM fit may be hard to test, even with 10 years of Fermi-LAT data,
especially if there is a mixture of DM and MSPs contributing to the signal, in
which case the implied DM cross section will be suppressed.
