Type Ia Supernovae: An Asymmetric Deflagration Model

TL;DR

This paper presents high-resolution 3D simulations of Type Ia supernovae, revealing asymmetric deflagration behavior that explains observed diversity and challenges the classic central-ignition model.

Contribution

First detailed 3D simulations of off-center ignition in Type Ia supernovae showing asymmetric explosion dynamics.

Findings

Asymmetric burning bubbles reach the surface at high velocities.

Burned mass is approximately 0.075 solar masses.

Kinetic energy of explosion is about 4.3 x 10^{49} ergs.

Abstract

We present the first high-resolution three-dimensional simulations of the deflagration phase of Type Ia supernovae that treat the entire massive white dwarf. We report the results of simulations in which ignition of the nuclear burning occurs slightly off-center. The subsequent evolution of the nuclear burning is surprisingly asymmetric with a growing bubble of hot ash rapidly rising to the stellar surface. Upon reaching the surface, the mass of burned material is $\approx 0.075 M_\sun$ and the kinetic energy is $4.3 \times 10^{49}$ ergs. The velocity of the top of the rising bubble approaches 8000 km s$^{-1}$. The amount of the asymmetry found in the model offers a natural explanation for the observed diversity in Type Ia supernovae. Our study strongly disfavors the classic central-ignition pure deflagration scenario by showing that the result is highly sensitive to details of the initial conditions.