Powerful explosions at Z=0 ?

TL;DR

This paper explores how rotation in primordial, metal-free stars can enhance supernova explosions, potentially transforming them from weak or failed events into powerful explosions, impacting early universe enrichment.

Contribution

It demonstrates that stellar rotation can significantly increase explosion energies of primordial stars, challenging previous assumptions of their weak or absent supernovae.

Findings

Rotation induces mass loss in primordial stars.

Fast spinning cores can lead to more energetic supernova explosions.

Rotation may cause primordial stars to enrich the early Universe more effectively.

Abstract

Metal-free stars are assumed to evolve at constant mass because of the very low stellar winds. This leads to large CO-core mass at the end of the evolution, so primordial stars with an initial mass between 25 and 85 Msol are expected to end as direct black holes, the explosion energy being too weak to remove the full envelope. We show that when rotation enters into play, some mass is lost because the stars are prone to reach the critical velocity during the main sequence evolution. Contrarily to what happens in the case of very low- but non zero-metallicity stars, the enrichment of the envelope by rotational mixing is very small and the total mass lost remains modest. The compactness of the primordial stars lead to a very inefficient transport of the angular momentum inside the star, so the profile of Omega(r) is close to Omega r^2 = const. As the core contracts, the rotation rate increases, and the star ends its life with a fast spinning core. Such a configuration has been shown to modify substantially the dynamics of the explosion. Where one expected a weak explosion or none at all, rotation might boost the explosion energy and drive a robust supernova. This will have important consequences in the way primordial stars enriched the early Universe.