Blandford-Znajek process as a gamma ray burst central engine

TL;DR

This paper explores the Blandford-Znajek mechanism as a potential central engine for gamma-ray bursts, focusing on electromagnetic energy extraction from rotating black holes with strong magnetic fields.

Contribution

It demonstrates the feasibility of the Blandford-Znajek process powering GRBs with high magnetic fields and shows the Poynting flux can originate mainly from the black hole rather than the disk.

Findings

High magnetic fields (~10^{15} G) are sufficient to power GRBs within 1000 seconds.

Electromagnetic energy extraction via the Blandford-Znajek process is viable as a GRB central engine.

Poynting flux can be predominantly supported by the black hole rather than the surrounding disk.

Abstract

We investigate the possibility that gamma-ray bursts are powered by a central engine consisting of a black hole with an external magnetic field supported by a surrounding disk or torus. The rotational energy of the black hole can be extracted electromagnetically as a Poynting flux, a mechanism proposed by Blandford and Znajek(1977). Recently observed magnetars indicate that some compact objects have very high magnetic fields, up to $10^{15}$ G, which is required to extract the energy within the duration of a GRB, i.e., in 1000 s or less. We demonstrate also that the Poynting flux need not be substantially dominated by the disk.