# Combustion in thermonuclear supernova explosions

## TL;DR

This paper reviews the combustion processes in thermonuclear supernovae, focusing on deflagrations and detonations, their modeling challenges, and their role in the explosion mechanism of Type Ia supernovae.

## Contribution

It provides a comprehensive overview of the physical mechanisms, theoretical models, and numerical techniques used to simulate combustion in supernova explosions, highlighting the complexity of modeling multi-scale phenomena.

## Key findings

- Different modes of combustion propagation are crucial in supernova explosions.
- Numerical modeling requires sophisticated techniques due to scale disparities.
- Understanding combustion transitions is key to supernova explosion models.

## Abstract

Type Ia supernovae are associated with thermonuclear explosions of white dwarf stars. Combustion processes convert material in nuclear reactions and release the energy required to explode the stars. At the same time, they produce the radioactive species that power radiation and give rise to the formation of the observables. Therefore, the physical mechanism of the combustion processes, as reviewed here, is the key to understand these astrophysical events. Theory establishes two distinct modes of propagation for combustion fronts: subsonic deflagrations and supersonic detonations. Both are assumed to play an important role in thermonuclear supernovae. The physical nature and theoretical models of deflagrations and detonations are discussed together with numerical implementations. A particular challenge arises due to the wide range of spatial scales involved in these phenomena. Neither the combustion waves nor their interaction with fluid flow and instabilities can be directly resolved in simulations. Substantial modeling effort is required to consistently capture such effects and the corresponding techniques are discussed in detail. They form the basis of modern multidimensional hydrodynamical simulations of thermonuclear supernova explosions. The problem of deflagration-to-detonation transitions in thermonuclear supernova explosions is briefly mentioned.