The Disruption of Giant Molecular Clouds by Radiation Pressure and the Efficiency of Star Formation in Galaxies

Understand

Star formation is slow, in the sense that the gas consumption time is much longer than the dynamical time.

• It is also inefficient; essentially all star formation in local galaxies takes place in giant molecular clouds (GMCs), but the fraction of a GMC converted to stars is very small, ~5%.
• In the most luminous starbursts, the GMC lifetime is shorter than the main sequence lifetime of even the most massive stars, so that supernovae can play no role in GMC disruption.
• We investigate the disruption of GMCs across a wide range of galaxies, from normal spirals to the densest starbursts; we take into account the effects of HII gas pressure, shocked stellar winds, protostellar jets, and radiation pressure produced by the absorption and scattering of starlight on dust grains.