Formation of Pop II star clusters in the aftermath of a pair instability supernova

Abstract

Pop II stars formed a few hundred million years after the Big Bang were key drivers of cosmic reionization and building blocks of high redshift galaxies. How and when these stars formed is a subject of ongoing research. We conduct cosmological radiation hydrodynamical simulations to investigate the formation of Pop II star clusters in dark matter halos forming at $z=10-25$ in the aftermath of a pair instability supernova (PISN). Our simulations model the formation of Pop III and Pop II stars in a self-consistent manner along with their radiative, chemical and SN feedback in halos of $\rm 5 \times 10^5- 7 \times 10^7~M_{\odot}$. We find that a PISN evacuates the gas from halos $\rm \leq 3 \times 10^{6}~M_{\odot}$ and thereafter shuts off in situ star formation for at-least 30 Myr. Pop II stellar clusters of $\rm 923~M_{\odot}$ and $\rm 6800~M_{\odot}$ form in halos of $\rm 3.5 \times 10^7~M_{\odot}$ and $\rm 7.2 \times 10^7~M_{\odot}$, respectively. The mode of star formation is highly episodic and mainly regulated by Pop II SN feedback. The average star formation rates are $\rm 10^{-5}-10^{-4}~M_{\odot}/yr$ and the star formation efficiency is less than 1\%.