Multidimensional Simulations of Thermonuclear Supernovae from the First Stars

TL;DR

This paper presents multidimensional simulations of pair-instability supernovae from first stars, revealing fluid instabilities that influence explosion dynamics and observational signatures, aiding future telescope detection efforts.

Contribution

Introduces new multidimensional radiation-hydrodynamics simulations of PSNe, capturing fluid instabilities and mixing effects in first star explosions.

Findings

Fluid instabilities develop at oxygen shell boundaries.

Reverse shocks induce Rayleigh-Taylor instabilities.

Instabilities affect ejecta mixing and observational signatures.

Abstract

Theoretical models suggest that the first stars in the universe could have been very massive, with typical masses $\gtrsim$ 100 \Msun. Many of them might have died as energetic thermonuclear explosions known as pair-instability supernovae (PSNe). We present multidimensional numerical simulations of PSNe with the new radiation-hydrodynamics code CASTRO. Our models capture all explosive burning and follow the explosion until the shock breaks out from the stellar surface. We find that fluid instabilities driven by oxygen and helium burning arise at the upper and lower boundaries of the oxygen shell $\sim$ 20 - 100 sec after the explosion begins. Later, when the shock reaches the hydrogen envelope a strong reverse shock forms that rapidly develops additional Rayleigh-Taylor instabilities. In red supergiant progenitors, the amplitudes of these instabilities are sufficient to mix the supernova's ejecta and alter its observational signature. Our results provide useful predictions for the detection of PSNe by forthcoming telescopes.