Inefficient star formation: The combined effects of magnetic fields and
  radiative feedback
  We investigate the effects of magnetic fields and radiative protostellar
feedback on the star formation process using self-gravitating radiation
magnetohydrodynamical calculations. We present results from a series of
calculations of the collapse of 50 solar mass molecular clouds with various
magnetic field strengths and with and without radiative transfer.
  We find that both magnetic fields and radiation have a dramatic impact on
star formation, though the two effects are in many ways complementary. Magnetic
fields primarily provide support on large scales to low density gas, whereas
radiation is found to strongly suppress small-scale fragmentation by increasing
the temperature in the high-density material near the protostars. With strong
magnetic fields and radiative feedback the net result is an inefficient star
formation process with a star formation rate of ~< 10% per free-fall time that
approaches the observed rate, although we have only been able to follow the
calculations for ~1/3 of a free-fall time beyond the onset of star formation.
