Pair Instability Supernovae: Light Curves, Spectra, and Shock Breakout

TL;DR

This paper models pair-instability supernovae, predicting their light curves, spectra, and shock breakout signatures, highlighting their potential observability at high redshift and their use in constraining progenitor star properties.

Contribution

It provides detailed simulations of PI SNe evolution and observational signatures across a range of initial masses and structures, including shock breakout predictions.

Findings

Light curves last for hundreds of days with luminosities up to 10^44 ergs/s.

Shock breakout transients reach luminosities of 10^45-10^46 ergs/s and last several hours.

High-redshift PI SNe could be detected through their shock breakout emission.

Abstract

For the initial mass range (140 < M < 260 Msun) stars die in a thermonuclear runaway triggered by the pair-production instability. The supernovae they make can be remarkably energetic (up to ~10^53 ergs) and synthesize considerable amounts of radioactive isotopes. Here we model the evolution, explosion, and observational signatures of representative pair-instability supernovae (PI SNe) spanning a range of initial masses and envelope structures. The predicted light curves last for hundreds of days and range in luminosity, from very dim to extremely bright, L ~ 10^44 ergs/s. The most massive events are bright enough to be seen at high redshift, but the extended light curve duration (~1 year) -- prolonged by cosmological time-dilation -- may make it difficult to detect them as transients. An alternative approach may be to search for the brief and luminous outbreak occurring when the explosion shock wave reaches the stellar surface. Using a multi-wavelength radiation-hydrodynamics code we calculate that, in the rest-frame, the shock breakout transients of PI SNe reach luminosities of 10^45-10^46 ergs/s, peak at wavelengths ~30-170 Angstroms, and last for several hours. We explore the detectability of PI SNe emission at high redshift, and discuss how observations of the light curves, spectra, and breakout emission can be used to constrain the mass, radius, and metallicity of the progenitor.