Convective vortices in collapsing stars

TL;DR

This paper investigates how convective vortices in collapsing stars influence supernova explosions, revealing how physical parameters affect vortex evolution and turbulence amplification during collapse.

Contribution

It introduces a simplified simulation model to analyze the impact of physical parameters on convective vortex evolution in stellar collapse.

Findings

Peak perturbation amplitude scales linearly with pre-collapse Mach number.

Inversely proportional relationship between amplitude and angular wavenumber.

Linear regime maintained for Mach numbers below approximately 0.2.

Abstract

Recent studies show that non-radial structures arising from massive star shell convection play an important role in shaping core-collapse supernova explosions. During the collapse phase, convective vortices generate acoustic waves that interact with the supernova shock. This amplifies turbulence in the post-shock region, contributing to explosion. We study how various physical parameters influence the evolution of these convective vortices during stellar collapse using simplified simulations. We model the collapsing star with a transonic Bondi flow and represent convection as solenoidal velocity perturbations. Our results are consistent with previous studies, demonstrating that the peak perturbation amplitude scales linearly with the pre-collapse convective Mach number and inversely with the angular wavenumber of convection. While the shell radius and width primarily determine the timescale of accretion, they have little impact on the peak perturbation amplitudes. Finally, we show that when the convective Mach number is below approximately 0.2, the dynamics remain within the linear regime.