The Observational Signatures of Primordial Pair-Instability Supernovae

TL;DR

This paper models the light curves and spectra of primordial pair-instability supernovae, suggesting they could be detected by JWST at high redshifts and highlighting the importance of early spectroscopy and mixing processes for understanding early cosmic explosions.

Contribution

It provides radiation hydrodynamical simulations of Pop III PISNe light curves and spectra, emphasizing the detectability and the role of mixing in progenitor mass determination.

Findings

Shock breakout pulse visible by JWST at z ~ 10-15

Vigorous mixing in core-collapse but not in PISNe

Early spectroscopy crucial for progenitor mass estimation

Abstract

Massive Population III stars from 140 - 260 solar masses ended their lives as pair-instability supernovae (PISNe), the most energetic thermonuclear explosions in the universe. Detection of these explosions could directly constrain the primordial IMF for the first time, which is key to the formation of the first galaxies, early cosmological reionization, and the chemical enrichment of the primeval IGM. We present radiation hydrodynamical calculations of Pop III PISN light curves and spectra performed with the RAGE code. We find that the initial radiation pulse due to shock breakout from the surface of the star, although attenuated by the Lyman-alpha forest, will still be visible by JWST at z ~ 10 - 15, and possibly out to z ~ 20 with strong gravitational lensing. We have also studied metal mixing at early stages of the explosion prior to breakout from the surface of the star with the CASTRO AMR code and find vigorous mixing in primordial core-collapse explosions but very little in PISNe. This implies that the key to determining progenitor masses of the first cosmic explosions is early spectroscopy just after shock breakout, and that multidimensional mixing is crucial to accurate low-mass Pop III SNe light curves and spectra.