  Stellar feedback in the form of radiation pressure and magnetically-driven
collimated outflows may limit the maximum mass that a star can achieve and
affect the star-formation efficiency of massive pre-stellar cores. Here we
present a series of 3D adaptive mesh refinement radiation-magnetohydrodynamic
simulations of the collapse of initially turbulent, massive pre-stellar cores.
Our simulations include radiative feedback from both the direct stellar and
dust-reprocessed radiation fields, and collimated outflow feedback from the
accreting stars. We find that protostellar outflows punches holes in the dusty
circumstellar gas along the star's polar directions, thereby increasing the
size of optically thin regions through which radiation can escape. Precession
of the outflows as the star's spin axis changes due to the turbulent accretion
flow further broadens the outflow, and causes more material to be entrained.
Additionally, the presence of magnetic fields in the entrained material leads
to broader entrained outflows that escape the core. We compare the injected and
entrained outflow properties and find that the entrained outflow mass is a
factor of $\sim$3 larger than the injected mass and the momentum and energy
contained in the entrained material are $\sim$25% and $\sim$5% of the injected
momentum and energy, respectively. As a result, we find that, when one includes
both outflows and radiation pressure, the former are a much more effective and
important feedback mechanism, even for massive stars with significant radiative
outputs.
