Effects of Rotation on the Minimum Mass of Primordial Progenitors of Pair Instability Supernovae

TL;DR

This study investigates how stellar rotation influences the minimum initial mass required for primordial stars to undergo pair instability supernovae, considering different metallicities and mass loss scenarios.

Contribution

It provides new estimates of the minimum main sequence mass for pair instability events, accounting for rotational mixing and metallicity effects, which were not thoroughly explored before.

Findings

Rotation lowers the minimum mass for pair instability supernovae.

Homogeneous evolution due to rotation increases the likelihood of pair instability at lower masses.

Mass loss raises the minimum mass thresholds for pair instability supernovae.

Abstract

The issue of which stars may reach the conditions of electron/positron pair formation instability is of importance to understand the final evolution both of the first stars and of contemporary stars. The criterion to enter the pair instability regime in density and temperature is basically controlled by the mass of the oxygen core. The main sequence masses that produce a given oxygen core mass are, in turn, dependent on metallicity, mass loss, and convective and rotationally-induced mixing. We examine the evolution of massive stars to determine the minimum main sequence mass that can encounter pair-instability effects, either a pulsational pair instability (PPISN) or a full-fledged pair-instability supernova (PISN). We concentrate on zero-metallicity stars with no mass loss subject to the Schwarzschild criterion for convective instability, but also explore solar metallicity and mass loss and the Ledoux criterion. As expected, for sufficiently strong rotationally-induced mixing, the minimum main sequence mass is encountered for conditions that induce effectively homogeneous evolution such that the original mass is converted almost entirely to helium and then to oxygen. For this case, we find that the minimum main sequence mass is ~40 Msun to encounter PPISN and ~65 Msun to encounter a PISN. When mass-loss is taken into account those mass limits become ~50 Msun for PPISN and ~80 Msun for PISN progenitors. The implications of these results for the first stars and for contemporary supernovae is discussed.