A runaway collision in a young star cluster as the origin of the brightest supernova

TL;DR

This paper proposes that the brightest supernova, SN 2006gy, originated from a stellar collision in a dense young star cluster, providing a new explanation for its progenitor's nature.

Contribution

It demonstrates that frequent stellar collisions in dense young clusters can produce supernovae like SN 2006gy, offering an alternative to single massive star progenitors.

Findings

Collision rates in dense clusters are sufficient to produce such supernovae.

A dense cluster of massive stars should be observable after the supernova fades.

Supports stellar mergers as a pathway for luminous supernovae.

Abstract

Supernova 2006gy in the galaxy NGC 1260 is the most luminous one recorded \cite{2006CBET..644....1Q, 2006CBET..647....1H, 2006CBET..648....1P, 2006CBET..695....1F}. Its progenitor might have been a very massive ($>100$ \msun) star \cite{2006astro.ph.12617S}, but that is incompatible with hydrogen in the spectrum of the supernova, because stars $>40$ \msun are believed to have shed their hydrogen envelopes several hundred thousand years before the explosion \cite{2005A&A...429..581M}. Alternatively, the progenitor might have arisen from the merger of two massive stars \cite{2007ApJ...659L..13O}. Here we show that the collision frequency of massive stars in a dense and young cluster (of the kind to be expected near the center of a galaxy) is sufficient to provide a reasonable chance that SN 2006gy resulted from such a bombardment. If this is the correct explanation, then we predict that when the supernova fades (in a year or so) a dense cluster of massive stars becomes visible at the site of the explosion.