The Role of Turbulence in Neutrino-Driven Core-Collapse Supernova Explosions

TL;DR

This study investigates how turbulence influences the explosion mechanism in core-collapse supernovae through high-resolution 3D simulations, revealing the critical role of turbulent ram pressure in enabling explosions at lower neutrino heating.

Contribution

It demonstrates that turbulent ram pressure, rather than just nonradial dynamics, is key to understanding differences in explosion conditions between 1D, 2D, and 3D supernova models.

Findings

Turbulent ram pressure facilitates supernova explosions at lower neutrino heating.

2D simulations tend to explode more easily than 3D due to higher turbulent energy at large scales.

Turbulent energy at large scales explains the discrepancy between 2D and 3D explosion outcomes.

Abstract

The neutrino-heated "gain layer" immediately behind the stalled shock in a core-collapse supernova is unstable to high-Reynolds-number turbulent convection. We carry out and analyze a new set of 19 high-resolution three-dimensional (3D) simulations with a three-species neutrino leakage/heating scheme and compare with spherically-symmetric (1D) and axisymmetric (2D) simulations carried out with the same methods. We study the postbounce supernova evolution in a $15$-$M_\odot$ progenitor star and vary the local neutrino heating rate, the magnitude and spatial dependence of asphericity from convective burning in the Si/O shell, and spatial resolution. Our simulations suggest that there is a direct correlation between the strength of turbulence in the gain layer and the susceptability to explosion. 2D and 3D simulations explode at much lower neutrino heating rates than 1D simulations. This is commonly explained by the fact that nonradial dynamics allows accreting material to stay longer in the gain layer. We show that this explanation is incomplete. Our results indicate that the effective turbulent ram pressure exerted on the shock plays a crucial role by allowing multi-D models to explode at a lower postshock thermal pressure and thus with less neutrino heating than 1D models. We connect the turbulent ram pressure with turbulent energy at large scales and in this way explain why 2D simulations are erroneously exploding more easily than 3D simulations.