Abstract
The physics of star formation at its extreme, in the nuclei of the largest
and densest star clusters in the universe - potential massive black hole
nurseries - has for decades eluded scrutiny. Spectroscopy of these systems has
been scarce, whereas theoretical claims have been made that radiation pressure
on dust grains somehow inhibits star formation. Here, we harness an accelerated
Monte Carlo radiation transport scheme to report a radiation hydrodynamical
simulation of super star cluster formation in turbulent clouds. We find that
radiation pressure reduces the global star formation efficiency by 30-35%, and
the star formation rate by 15-50%, both relative to a radiation-free control
run. Overall, radiation pressure is ineffective in limiting the gas supply for
star formation and the final stellar mass of the most massive cluster is $\sim
1.3\times10^6\,M_ødot$. The limited impact as compared to that implied by
idealized theoretical models is attributed to a radiation-matter
anti-correlation in the supersonically turbulent, gravitationally collapsing
medium. In isolated regions outside massive clusters, where the gas
distribution is less disturbed, radiation pressure is more effective in
limiting star formation. The resulting stellar density at the cluster core is
$10^8\,M_ødot\,pc^-3$, with stellar velocity dispersion
$70\,km\,s^-1$. We conclude that the super star cluster
nucleus is propitious to the formation of very massive stars via dynamical core
collapse and stellar merging. We speculate that the very massive star may avoid
the claimed catastrophic mass loss by continuing to accrete dense gas
condensing from a gravitationally-confined ionized phase.
Description
[1709.07539] Radiation pressure in super star cluster formation
Links and resources
Tags