Jet Luminosity from Neutrino-Dominated Accretion Flows in GRBs

TL;DR

This paper models jet luminosity in gamma-ray bursts driven by magnetohydrodynamic processes in hyperaccretion disks, highlighting the impact of accretion regimes and black hole spin on jet efficiency and variability.

Contribution

It provides a detailed estimation of jet luminosity based on accretion parameters, emphasizing the role of neutrino cooling and accretion regime transitions in GRB jet production.

Findings

Jet luminosity peaks when neutrino cooling is efficient.

Significant luminosity jump at the ADAF to NDAF transition.

Rapid black hole spin enhances jet energy output.

Abstract

A hyperaccretion disk around a stellar-mass black hole is a plausible model for the central engine that powers gamma-ray bursts (GRBs). We estimate the luminosity of a jet driven by magnetohydrodynamic processes such as the Blandford-Znajek (BZ) mechanism as a function of mass accretion rate, the black hole mass, and other accretion parameters. We show that the jet is most efficient when the accretion flow is cooled via optically-thin neutrino emission, and that its luminosity is much larger than the energy deposition rate through neutrino annihilation provided that the black hole is spinning rapidly enough. Also, we find a significant jump in the jet luminosity at the transition mass accretion rate between the advection dominated accretion flow (ADAF) regime and the neutrino-dominated accretion flow (NDAF) regime. This may cause the large variability observed in the prompt emission of GRBs.