The Early Evolution of Primordial Pair-Instability Supernovae

TL;DR

This study uses advanced simulations to show that primordial pair-instability supernovae exhibit minimal mixing, which affects their observational signatures and helps distinguish them from core-collapse supernovae.

Contribution

The paper provides the first detailed numerical simulations of the early evolution of Population III pair-instability supernovae using the CASTRO code, revealing minimal mixing in massive cases.

Findings

Most 150-250 Msun pair-instability supernovae show no mixing after surface breakout.

Lack of mixing delays the appearance of heavy metal emission lines in light curves.

Results suggest different observational signatures compared to core-collapse supernovae.

Abstract

The observational signatures of the first cosmic explosions and their chemical imprint on second-generation stars both crucially depend on how heavy elements mix within the star at the earliest stages of the blast. We present numerical simulations of the early evolution of Population III pair-instability supernovae with the new adaptive mesh refinement code CASTRO. In stark contrast to 15 - 40 Msun core-collapse primordial supernovae, we find no mixing in most 150 - 250 Msun pair-instability supernovae out to times well after breakout from the surface of the star. This may be the key to determining the mass of the progenitor of a primeval supernova, because vigorous mixing will cause emission lines from heavy metals such as Fe and Ni to appear much sooner in the light curves of core-collapse supernovae than in those of pair-instability explosions. Our results also imply that unlike low-mass Pop III supernovae, whose collective metal yields can be directly compared to the chemical abundances of extremely metal-poor stars, further detailed numerical simulations will be required to determine the nucleosynthetic imprint of very massive Pop III stars on their direct descendants.