Low Mach Number Modeling of Convection in Helium Shells on Sub-Chandrasekhar White Dwarfs II: Bulk Properties of Simple Models

TL;DR

This study uses 3D low Mach number simulations to analyze helium shell convection on white dwarfs, revealing diverse behaviors and supporting the double detonation supernova model.

Contribution

It provides the first detailed 3D bulk property analysis of helium shell convection in white dwarfs, highlighting the importance of dynamic convection in supernova progenitors.

Findings

Diverse convection outcomes including quasi-equilibrium and runaway.

3D convection significantly influences the conditions for supernova explosions.

Results support the viability of the double detonation model.

Abstract

The dynamics of helium shell convection driven by nuclear burning establish the conditions for runaway in the sub-Chandrasekhar mass, double detonation model for Type Ia supernovae, as well as for a variety of other explosive phenomena. We explore these convection dynamics for a range of white dwarf core and helium shell masses in three dimensions using the low Mach number hydrodynamics code Maestro. We present calculations of the bulk properties of this evolution, including time-series evolution of global diagnostics, lateral averages of the 3D state, and the global 3D state. We find a variety of outcomes including quasi-equilibrium, localized runaway, and nova-like runaway. Our results suggest the double detonation progenitor model is promising, that 3D, dynamic convection plays a key role, and that these systems warrant further study.