Nucleosynthesis in Two-Dimensional Delayed Detonation Models of Type Ia Supernova Explosions

TL;DR

This paper investigates nucleosynthesis in two-dimensional models of Type Ia supernova explosions, comparing pure deflagration, spherical delayed detonation, and asymmetric ignition scenarios to understand their yields and structures.

Contribution

It introduces multidimensional simulation approaches for Type Ia supernovae, highlighting differences in nucleosynthetic yields and explosion structures compared to traditional one-dimensional models.

Findings

Delayed detonations produce layered structures consistent with galactic chemical constraints.

Asymmetric ignition leads to off-center distributions of electron-capture elements.

Detonation occurs at lower densities, affecting nucleosynthesis outcomes.

Abstract

The nucleosynthetic characteristics of various explosion mechanisms of Type Ia supernovae (SNe Ia) is explored based on three two-dimensional explosion simulations representing extreme cases: a pure turbulent deflagration, a delayed detonation following an approximately spherical ignition of the initial deflagration, and a delayed detonation arising from a highly asymmetric deflagration ignition. Apart from this initial condition, the deflagration stage is treated in a parameter-free approach. The detonation is initiated when the turbulent burning enters the distributed burning regime. This occurs at densities around $10^{7}$ g cm$^{-3}$ -- relatively low as compared to existing nucleosynthesis studies for one-dimensional spherically symmetric models. The burning in these multidimensional models is different from that in one-dimensional simulations as the detonation wave propagates both into unburned material in the high density region near the center of a white dwarf and into the low density region near the surface. Thus, the resulting yield is a mixture of different explosive burning products, from carbon-burning products at low densities to complete silicon-burning products at the highest densities, as well as electron-capture products synthesized at the deflagration stage. In contrast to the deflagration model, the delayed detonations produce a characteristic layered structure and the yields largely satisfy constraints from Galactic chemical evolution. In the asymmetric delayed detonation model, the region filled with electron capture species (e.g., $^{58}$Ni, $^{54}$Fe) is within a shell, showing a large off-set, above the bulk of $^{56}$Ni distribution, while species produced by the detonation are distributed more spherically (abridged).