Pulsational pair instability as an explanation for the most luminous supernovae

TL;DR

This paper proposes that pulsational pair instability in massive stars can explain extremely luminous supernovae like SN 2006gy through shell collisions caused by interior instabilities, leading to multiple energetic outbursts.

Contribution

It introduces a model where pulsational pair instability causes multiple shell ejections and collisions, explaining superluminous supernovae beyond traditional core-collapse mechanisms.

Findings

Model matches observed light curve of SN 2006gy

Multiple shell ejections produce superluminous explosions

Stars can undergo several supernova-like outbursts

Abstract

The extremely luminous supernova SN 2006gy challenges the traditional view that the collapse of a stellar core is the only mechanism by which a massive star makes a supernova, because it seems too luminous by more than a factor of ten. Here we report that the brightest supernovae in the modern Universe arise from collisions between shells of matter ejected by massive stars that undergo an interior instability arising from the production of electron-positron pairs. This "pair instability" leads to explosive burning that is insufficient to unbind the star, but ejects many solar masses of the envelope. After the first explosion, the remaining core contracts and searches for a stable burning state. When the next explosion occurs, several solar masses of material are again ejected, which collide with the earlier ejecta. This collision can radiate 1E50 erg of light, about a factor of ten more than an ordinary supernova. Our model is in good agreement with the observed light curve for SN 2006gy and also shows that some massive stars can produce more than one supernova-like outburst.