Efficiency of Neutrino Annihilation around Spinning Black Holes

TL;DR

This paper calculates the efficiency of neutrino annihilation around spinning black holes using a relativistic, geodesic-tracing method, showing how it depends on accretion rate and black hole spin, aiding in understanding GRB engines.

Contribution

It provides a fully relativistic calculation of neutrino annihilation efficiency around Kerr black holes, highlighting its dependence on accretion rate and spin, independent of neutrino transport details.

Findings

Efficiency depends on accretion rate and black hole spin

Efficiency is independent of neutrino transport details in the opaque zone

Results identify disks capable of powering GRBs

Abstract

A fraction of neutrino emission from GRB accretion disks annihilates above the disk, creating e+- plasma that can drive GRB explosions. We calculate the efficiency of this annihilation using the recent detailed model of hyper-accretion disks around Kerr black holes. Our calculation is fully relativistic and based on a geodesic-tracing method. We find that the efficiency is a well-defined function of (1) accretion rate and (2) spin of the black hole. It is practically independent of the details of neutrino transport in the opaque zone of the disk. The results help identify the accretion disks whose neutrino emission can power GRBs.