Inefficient star formation: The combined effects of magnetic fields and radiative feedback

TL;DR

This study uses advanced simulations to show that magnetic fields and radiative feedback significantly reduce star formation efficiency by supporting large-scale gas and suppressing small-scale fragmentation, aligning with observed rates.

Contribution

It provides a comprehensive analysis of how magnetic fields and radiative feedback jointly influence star formation, highlighting their complementary roles in reducing efficiency.

Findings

Magnetic fields support large-scale gas against collapse.

Radiative feedback suppresses small-scale fragmentation.

Star formation rate approaches observed values (~10% per free-fall time).

Abstract

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.