Survival of star-forming giant clumps in high-redshift galaxies

Abstract

We investigate the effects of radiation pressure from stars on the survival of the star-forming giant clumps in high-redshift massive disc galaxies, during the most active phase of galaxy formation. The clumps, typically of mass ∼108–109 M and radius ∼0.5–1 kpc, are formed in the turbulent gas-rich discs by violent gravitational instability and then migrate into a central bulge in ∼10 dynamical times. We show that the survival or disruption of these clumps under the influence of stellar feedback depends critically on the rate at which they form stars. If they convert a few per cent of their gas mass to stars per free-fall time, as observed for all local star-forming systems and implied by the Kennicutt–Schmidt law, they cannot be disrupted. Only if clumps convert most of their mass to stars in a few free-fall times can feedback produce significant gas expulsion. We consider whether such rapid star formation is likely in high-redshift giant clumps.