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