Radiation-Hydrodynamic Simulations of the Formation of Orion-Like Star
  Clusters II. The Initial Mass Function from Winds, Turbulence, and Radiation
  [abridged] We report a series of simulations of the formation of a star
cluster similar to the Orion Nebula Cluster (ONC), including both radiative
transfer and protostellar outflows, and starting from both smooth and
self-consistently turbulent initial conditions. Each simulation forms >150
stars and brown dwarfs, yielding a stellar mass distribution from < 0.1 to > 10
Msun. We show that a simulation that begins with self-consistently turbulence
embedded in a larger turbulent volume, and that includes protostellar outflows,
produces an initial mass function (IMF) consistent both with that of the ONC
and the Galactic field. This is the first simulation published to date that
reproduces the observed IMF in a cluster large enough to contain massive stars,
and where the result is determined by a fully self-consistent calculation of
gas thermodynamics. This simulation also produces a star formation rate that,
while still somewhat too high, is much closer to observed values than if we
omit either the larger turbulent volume or the outflows. Moreover, we show that
the combination of outflows, self-consistently turbulent initial conditions,
and turbulence continually fed by motions on scales larger than that of the
protocluster yields an IMF that is in agreement with observations and invariant
with time, resolving the "overheating" problem in which simulations without
these features have an IMF peak that shifts to progressively higher masses over
time. The simulation that matches the observed IMF also reproduces the observed
trend of stellar multiplicity strongly increasing with mass. We show that this
simulation produces massive stars from distinct massive cores whose properties
are consistent with those of observed massive cores. However, the stars formed
in these cores also undergo dynamical interactions that naturally produce
Trapezium-like hierarchical multiple systems.
