Final Evolution and Delayed Explosions of Spinning White Dwarfs in Single Degenerate Models for Type Ia Supernovae

TL;DR

This paper explores how spinning white dwarfs in single degenerate models can delay Type Ia supernova explosions due to angular momentum loss, with potential delays of several billion years before explosion or collapse.

Contribution

It introduces a model where angular momentum loss in rotating white dwarfs causes delayed supernova explosions, expanding understanding of supernova timing in single degenerate scenarios.

Findings

Delayed SNe Ia can occur if white dwarf mass is between 1.38 and 1.43 solar masses.

Delay times can reach several billion years, depending on angular momentum loss.

White dwarfs may collapse if delay exceeds approximately 3 billion years.

Abstract

We study the occurrence of delayed SNe~Ia in the single degenerate (SD) scenario. We assume that a massive carbon-oxygen (CO) white dwarf (WD) accretes matter coming from a companion star, making it to spin at the critical rate. We assume uniform rotation due to magnetic field coupling. The carbon ignition mass for non-rotating WDs is M_{ig}^{NR} \approx 1.38 M_{\odot}; while for the case of uniformly rotating WDs it is a few percent larger (M_{ig}^{R} \approx 1.43 M_{\odot}). When accretion rate decreases, the WD begins to lose angular momentum, shrinks, and spins up; however, it does not overflow its critical rotation rate, avoiding mass shedding. Thus, angular momentum losses can lead the CO WD interior to compression and carbon ignition, which would induce an SN~Ia. The delay, largely due to the angular momentum losses timescale, may be large enough to allow the companion star to evolve to a He WD, becoming undetectable at the moment of explosion. This scenario supports the occurrence of delayed SNe~Ia if the final CO WD mass is 1.38 M_{\odot} < M < 1.43 M_{\odot}. We also find that if the delay is longer than ~3 Gyr, the WD would become too cold to explode, rather undergoing collapse.