Type Ia supernovae and the DD scenario

TL;DR

This paper reviews the ongoing debate about whether Type Ia supernovae originate from single degenerate systems or double degenerate mergers, highlighting conflicting evidence and unresolved issues.

Contribution

It provides a critical review of the controversies surrounding the double degenerate scenario for Type Ia supernovae.

Findings

Delay time distribution supports DD scenario for late explosions

Contradiction with the idea that WD mergers lead to neutron stars

Highlights unresolved issues in supernova progenitor models

Abstract

Type Ia supernovae are thought to be the outcome of the thermonuclear explosion of a white dwarf in a close binary system. Two possible scenarios, not necessarily incompatible, have been advanced. One assumes a white dwarf that accretes matter from a nondegenerate companion (the single degenerate scenario), the other assumes two white dwarfs that merge as a consequence of the emission of gravitational waves (the double degenerate scenario). The delay time distribution of star formation bursts strongly suggests that the DD scenario should be responsible of the late time explosions, but this contradicts the common wisdom that the outcome of the merging of two white dwarfs is an accretion induced collapse to a neutron star. In this contribution we review some of the most controversial issues of this problem.