Evolution of black hole mass and spin in collapsars

TL;DR

This paper explores how the evolution of black hole mass and spin during collapsar events influences long gamma-ray bursts, focusing on accretion scenarios and initial angular momentum distributions.

Contribution

It introduces a detailed analysis of black hole spin and mass evolution in collapsars, emphasizing the role of initial stellar rotation and accretion processes.

Findings

Black hole spin increases with accretion of angular momentum.

Initial stellar rotation significantly affects black hole properties.

Different accretion scenarios lead to varied jet energetics.

Abstract

We investigate the collapsar scenario for the long gamma ray bursts. The energetics % of explosions in the $\gamma$-ray band are consistent with the binding energy of a progenitor star. The events duration times, lightcurve profiles, variability, and connection with supernovae, are still subject of many studies. In our scenario, the evolved progenitor star is collapsing onto a spinning black hole formed from the compact core. The accretion via rotationally supported torus powers the ejection of relativistic jets. The rotational energy of the black hole is presumably transported to the remote jet and mediated by magnetic fields. The rotation of pre-supernova star is a key property of the model. In our study, we investigate different accretion scenarios and various distributions of initial angular momentum in the envelope, that affect the spinning up the black hole and its mass increment.