Collisional N-Body Dynamics Coupled to Self-Gravitating
  Magnetohydrodynamics Reveals Dynamical Binary Formation
  We describe a star cluster formation model that includes individual star
formation from self-gravitating, magnetized gas, coupled to collisional stellar
dynamics. The model uses the Astrophysical Multi-purpose Software Environment
(AMUSE) to integrate an adaptive-mesh magnetohydrodynamics code (FLASH) with a
fourth order Hermite N-body code (ph4), a stellar evolution code (SeBa), and a
method for resolving binary evolution (multiples). This combination yields
unique star formation simulations that allow us to study binaries formed
dynamically from interactions with both other stars and dense, magnetized gas
subject to stellar feedback during the birth and early evolution of stellar
clusters. We find that for massive stars, our simulations are consistent with
the observed dynamical binary fractions and mass ratios. However, our binary
fraction drops well below observed values for lower mass stars, presumably due
to unincluded binary formation during initial star formation. Further, we
observe a build up of binaries near the hard-soft boundary that may be an
important mechanism driving early cluster contraction.
