3D simulations of Rayleigh-Taylor mixing in core-collapse SNe with CASTRO

TL;DR

This study uses 2D and 3D simulations with the CASTRO code to analyze Rayleigh-Taylor mixing in supernova explosions, revealing that 2D models can approximate 3D results for certain conditions, but initial asymmetries require 3D modeling.

Contribution

It demonstrates that 2D simulations can effectively capture key mixing features of supernova explosions, reducing computational costs compared to 3D models, especially for symmetric cases.

Findings

3D Rayleigh-Taylor growth is initially faster than in 2D.

Mixing is more extensive in 3D due to finger interactions.

2D simulations can approximate 3D results for symmetric explosions.

Abstract

We present multidimensional simulations of the post-explosion hydrodynamics in three different 15 solar mass supernova models with zero, 10^{-4} solar metallicity, and solar metallicities. We follow the growth of the Rayleigh-Taylor instability that mixes together the stellar layers in the wake of the explosion. Models are initialized with spherically symmetric explosions and perturbations are seeded by the grid. Calculations are performed in two-dimensional axisymmetric and three-dimensional Cartesian coordinates using the new Eulerian hydrodynamics code, CASTRO. We find as in previous work, that Rayleigh-Taylor perturbations initially grow faster in 3D than in 2D. As the Rayleigh-Taylor fingers interact with one another, mixing proceeds to a greater degree in 3D than in 2D, reducing the local Atwood number and slowing the growth rate of the instability in 3D relative to 2D. By the time mixing has stopped, the width of the mixed region is similar in 2D and 3D simulations provided the Rayleigh-Taylor fingers show significant interaction. Our results imply that 2D simulations of light curves and nucleosynthesis in supernovae (SNe) that die as red giants may capture the features of an initially spherically symmetric explosion in far less computational time than required by a full 3D simulation. However, capturing large departures from spherical symmetry requires a significantly perturbed explosion. Large scale asymmetries cannot develop through an inverse cascade of merging Rayleigh-Taylor structures; they must arise from asymmetries in the initial explosion.