Testing Blandford-Znajek mechanism in black hole hyperaccretion flows for long-duration gamma-ray bursts

TL;DR

This study evaluates the Blandford-Znajek mechanism as a central engine for long-duration gamma-ray bursts by analyzing a large sample of GRBs and constraining accretion rates based on jet properties.

Contribution

It provides the first comprehensive analysis of BZ mechanism viability in long GRBs using observational data and constrains accretion rates for different black hole spins.

Findings

BZ mechanism can power long GRB prompt emissions at reasonable accretion rates.

Distributions of GRB luminosities and durations support BZ as a plausible engine.

Constraints on accretion rates vary with black hole spin.

Abstract

Long-duration gamma-ray bursts (GRBs) are generally related to the core-collapse of massive stars. In the collapsar scenario, a rotating stellar-mass black hole (BH) surrounded by a hyperaccretion disk has been considered as one of the plausible candidates of GRB central engines. In this paper, we work on a sample including 146 long GRBs with significant jet break features in the multi-band afterglows. The jet opening angles can be then obtained by the jet break time. By asumming GRB jets powered by Blandford-Znajek (BZ) mechanism in the BH hyperaccretion system, we analyze the distributions of the long GRB luminosities and durations in the samples, and constrain the accretion rates for the different BH spins. As the results, we find that the BZ mechanism is so powerful making it possible to interpret the long GRB prompt emissions within the reasonably accretion rates.