The Dominance of Neutrino-Driven Convection in Core-Collapse Supernovae

TL;DR

This paper demonstrates that neutrino-driven convection is the primary mechanism behind post-shock turbulence in core-collapse supernovae, supported by simulations showing characteristic convection signatures and scaling relations.

Contribution

The study provides the first detailed comparison and scaling relations for neutrino-driven convection in 3D supernova simulations, establishing it as the dominant instability mechanism.

Findings

Convective fluxes and energies align with buoyancy-driven convection expectations.

Positive convective flux correlates with buoyant driving regions.

Convective luminosity and dissipation scale with neutrino power.

Abstract

Multi-dimensional instabilities have become an important ingredient in core-collapse supernova (CCSN) theory. Therefore, it is necessary to understand the driving mechanism of the dominant instability. We compare our parameterized three-dimensional CCSN simulations with other buoyancy-driven simulations and propose scaling relations for neutrino-driven convection. Through these comparisons, we infer that buoyancy-driven convection dominates post-shock turbulence in our simulations. In support of this inference, we present four major results. First, the convective fluxes and kinetic energies in the neutrino-heated region are consistent with expectations of buoyancy-driven convection. Second, the convective flux is positive where buoyancy actively drives convection, and the radial and tangential components of the kinetic energy are in rough equipartition (i.e. K_r ~ K_{\theta} + K_{\phi}). Both results are natural consequences of buoyancy-driven convection, and are commonly observed in simulations of convection. Third, buoyant driving is balanced by turbulent dissipation. Fourth, the convective luminosity and turbulent dissipation scale with the driving neutrino power. In all, these four results suggest that in neutrino-driven explosions, the multi-dimensional motions are consistent with neutrino-driven convection.