Jet Luminosity From Neutrino-Dominated Accretion Flows in Gamma-Ray Bursts

TL;DR

This paper models jet luminosity from neutrino-cooled accretion disks around spinning black holes, showing that magnetic mechanisms can produce jets powerful enough to explain gamma-ray bursts.

Contribution

It estimates jet luminosity driven by magnetic fields in neutrino-cooled accretion flows, highlighting conditions for maximum efficiency and relevance to GRB energetics.

Findings

Jet luminosity exceeds neutrino-antineutrino annihilation energy deposition.

Maximum jet efficiency occurs when accretion flow is neutrino-cooled.

High accretion rates on spinning black holes can produce GRB-level jets.

Abstract

A hyperaccretion disk formed around a stellar mass black hole is a plausible model for the central engine that powers gamma-ray bursts (GRBs). If the central black hole rotates and a poloidal magnetic field threads its horizon, a powerful relativistic jet may be driven by a process resembling the Blandford-Znajek mechanism. We estimate the luminosity of such a jet assuming that the poloidal magnetic field strength is comparable to the inner accretion disk pressure. We show that the jet efficiency attains its maximal value when the accretion flow is cooled via optically-thin neutrino emission. The jet luminosity is much larger than the energy deposition through neutrino-antineutrino annihilation provided that the black hole is spinning rapidly enough. When the accretion rate onto a rapidly spinning black hole is large enough (> 0.003-0.01M_sun/sec), the predicted jet luminosity is sufficient to drive a GRB.