The Single-Degenerate Channel Leads to Type Iax and Not Type Ia Supernovae due to Premature Ignition

TL;DR

This study uses 3D simulations to show that the single-degenerate channel mainly produces Type Iax supernovae through premature ignition at sub-Chandrasekhar masses, not normal Type Ia supernovae.

Contribution

The paper demonstrates that the single-degenerate channel leads to Type Iax supernovae due to premature ignition, challenging previous assumptions about its role in producing normal SNe Ia.

Findings

Accreting white dwarfs ignite prematurely at sub-Chandrasekhar masses.

Only white dwarfs reaching 1.37 solar masses produce normal SNe Ia.

The SD channel predominantly explains Type Iax supernovae, not normal SNe Ia.

Abstract

Type Ia supernovae (SNe Ia) are a critical tool for cosmology and galactic enrichment, yet the progenitor systems of normal SNe Ia remain a central puzzle. The long-debated single-degenerate (SD) channel, where a white dwarf (WD) accretes mass from a companion, faces major observational conflicts. Here, we present 3D hydrodynamic simulations that resolve these tensions by showing a fundamental dichotomy: accreting WDs predominantly ignite prematurely at sub-Chandrasekhar masses, producing low-energy, incomplete explosions consistent with Type Iax supernovae. Only WDs reaching a narrow mass threshold of 1.37 solar mass undergo complete destruction, characteristic of normal SNe Ia. This "safety valve" mechanism effectively recasts the SD channel as the main pathway to SNe Iax, not normal SNe Ia, providing a unified explanation for the observed scarcity of progenitor signatures in the latter and suggesting alternative channels dominate normal SNe Ia production.