Pair creation supernovae at low and high redshift

TL;DR

This paper investigates the formation conditions and occurrence rates of pair creation supernovae (PCSNe) across different metallicities and stellar rotation rates, revealing two distinct progenitor types and their potential frequencies in the universe.

Contribution

It identifies two types of PCSN progenitors based on rotation speed and metallicity, and estimates their occurrence rates at various redshifts, expanding understanding of PCSNe origins.

Findings

Hydrogen-rich PCSNe can occur at metallicities up to Z$_{\odot}$/3.

Two progenitor types: fast rotators (Wolf-Rayet stars) and slow rotators (yellow hypergiants).

Estimated local universe rate: one PCSN per 1000 supernovae.

Abstract

Pair creation supernovae (PCSN) are thought to be produced from very massive low metallicity stars. The spectacularly bright SN 2006gy does show signatures expected from PCSNe. Here, we investigate the metallicity threshold below which PCSN can form and estimate their occurrence rate. We perform stellar evolution calculations for stars of 150$\mso$ and 250$\mso$ of low metallicity (Z$_{\odot}$/5 and Z$_{\odot}$/20), and analyze their mass loss rates. We find that the bifurcation between quasi-chemically homogeneous evolution for fast rotation and conventional evolution for slower rotation, which has been found earlier for massive low metallicity stars, persists in the mass range considered here. Consequently, there are two separate PCSN progenitor types: (I) Fast rotators produce PCSNe from very massive Wolf-Rayet stars, and (II) Slower rotators that generate PCSNe in hydrogen-rich massive yellow hypergiants. We find that hydrogen-rich PCSNe could occur at metallicities as high as Z$_{\odot}$/3, which -- assuming standard IMFs are still valid to estimate their birth rates -- results in a rate of about one PCSN per 1000 supernovae in the local universe, and one PCSN per 100 supernovae at a redshift of $z=5$. PCSNe from WC-type Wolf-Rayet stars are restricted to much lower metallicity.