Possible Detection of a Pair Instability Supernova in the Modern Universe, and Implications for the First Stars

TL;DR

This paper discusses the potential identification of a pair instability supernova in the modern universe, based on observations of SN 2006gy, which challenges existing models of massive star evolution and supernova mechanisms.

Contribution

It proposes SN 2006gy as the first candidate for a genuine pair instability supernova in the current universe, with implications for stellar evolution theories.

Findings

SN 2006gy radiated over 10^51 ergs of luminous energy.

It likely originated from an extremely massive star with little mass loss.

The supernova's properties suggest it may be a pair instability supernova.

Abstract

SN 2006gy radiated far more energy in visual light than any other supernova so far, and potential explanations for its energy demands have implications for galactic chemical evolution and the deaths of the first stars. It remained bright for over 200 days, longer than any normal supernova, and it radiated more than 1e51 ergs of luminous energy at visual wavelengths. I argue that this Type IIn supernova was probably the explosion of an extremely massive star like Eta Carinae that retained its hydrogen envelope when it exploded, having suffered relatively little mass loss during its lifetime. That this occurred at roughly Solar metallicity challenges current paradigms for mass loss in massive-star evolution. I explore a few potential explanations for SN2006gy's power source, involving either circumstellar interaction, or instead, the decay of 56Ni. If SN 2006gy was powered by the conversion of shock energy into light, then the conditions must be truly extraordinary and traditional interaction models don't work. If SN 2006gy was powered by radioactive decay, then the uncomfortably huge 56Ni mass requires that the star exploded as a pair instability supernova. The mere possibility of this makes SN 2006gy interesting, especially at this meeting, because it is the first good candidate for a genuine pair instability supernova.