Star formation efficiencies of molecular clouds in a galactic center
  environment
  We use the Arepo moving mesh code to simulate the evolution of molecular
clouds exposed to a harsh environment similar to that found in the galactic
center (GC), in an effort to understand why the star formation efficiency (SFE)
of clouds in this environment is so small. Our simulations include a simplified
treatment of time-dependent chemistry and account for the highly non-isothermal
nature of the gas and the dust. We model clouds with a total mass of 1.3x10^5
M_{sun} and explore the effects of varying the mean cloud density and the
virial parameter, alpha = E_{kin}/|E_{pot}|. We vary the latter from alpha =
0.5 to alpha = 8.0, and so many of the clouds that we simulate are
gravitationally unbound. We expose our model clouds to an interstellar
radiation field (ISRF) and cosmic ray flux (CRF) that are both a factor of 1000
higher than the values found in the solar neighbourhood. As a reference, we
also run simulations with local solar neighbourhood values of the ISRF and the
CRF in order to better constrain the effects of the extreme conditions in the
GC on the SFE. Despite the harsh environment and the large turbulent velocity
dispersions adopted, we find that all of the simulated clouds form stars within
less than a gravitational free-fall time. Increasing the virial parameter from
alpha = 0.5 to alpha = 8.0 decreases the SFE by a factor ~4-10, while
increasing the ISRF/CRF by a factor of 1000 decreases the SFE again by a factor
~2-6. However, even in our most unbound clouds, the SFE remains higher than
that inferred for real GC clouds. We therefore conclude that high levels of
turbulence and strong external heating are not enough by themselves to lead to
a persistently low SFE at the center of the Galaxy.
