Merging White Dwarfs and Thermonuclear Supernovae

TL;DR

This paper proposes that thermonuclear supernovae originate from mergers of white dwarfs rather than the traditional near-Chandrasekhar mass ignition, offering new explanations and observational tests for these explosive events.

Contribution

It introduces the idea that white dwarf mergers, including sub-Chandrasekhar mass remnants, are the primary cause of thermonuclear supernovae, challenging previous models.

Findings

Mergers of white dwarfs can produce thermonuclear supernovae.

Observational tests can distinguish between merger and traditional models.

Electron capture signatures can inform the explosion mechanism.

Abstract

Thermonuclear supernovae result when interaction with a companion reignites nuclear fusion in a carbon-oxygen white dwarf, causing a thermonuclear runaway, a catastrophic gain in pressure, and the disintegration of the whole white dwarf. It is usually thought that fusion is reignited in near-pycnonuclear conditions when the white dwarf approaches the Chandrasekhar mass. I briefly describe two long-standing problems faced by this scenario, and our suggestion that these supernovae instead result from mergers of carbon-oxygen white dwarfs, including those that produce sub-Chandrasekhar mass remnants. I then turn to possible observational tests, in particular those that test the absence or presence of electron captures during the burning.