SN Ia DDT Explosions Powered by the Zeldovich Reactivity Gradient Mechanism

TL;DR

This paper investigates the conditions leading to Type Ia supernova explosions by modeling turbulence and nuclear burning in white dwarfs, highlighting the role of the Zel'dovich reactivity gradient mechanism in initiating detonations.

Contribution

It introduces a turbulence-based model demonstrating how reactivity gradients can trigger detonations in white dwarf explosions, advancing understanding of supernova mechanisms.

Findings

Reactivity gradients can initiate detonations without acoustic waves.

Turbulence inhomogeneity influences detonation initiation.

Model aligns with observed supernova explosion timescales.

Abstract

The aim of this work is to identify and explain the necessary conditions required for an energetic explosion of a Chandrasekhar-mass white dwarf. We construct and analyze weakly compressible turbulence models with nuclear burning effects for carbon/oxygen plasma at a density expected for deflagration-to-detonation transition (DDT) to occur. We observe formation of carbon deflagrations and transient carbon detonations at early times. As turbulence becomes increasingly inhomogeneous, sustained carbon detonations are initiated by the Zel'dovich reactivity gradient mechanism. The fuel is suitably preconditioned by the action of compressive turbulent modes with wavelength comparable to the size of resolved turbulent eddies; no acoustic wave is involved in this process. Oxygen detonations are initiated either aided by reactivity gradients or by collisions of carbon detonations. The observed evolutionary timescales are found sufficiently short for the above process to occur in the expanding, centrally ignited massive white dwarf. The inhomogeneous conditions produced prior to DDT might be of consequence for the chemical composition of the outer ejecta regions of SN Ia from the single degenerate channel, and offer potential for validation of the proposed model.