Hyperaccreting Disks around Neutrons Stars and Magnetars for GRBs: Neutrino Annihilation and Strong Magnetic Fields

TL;DR

This paper explores how hyperaccreting disks around neutron stars and magnetars can power gamma-ray bursts through neutrino annihilation and magnetic fields, highlighting the enhanced efficiency compared to black hole systems.

Contribution

It demonstrates that neutron star disks produce higher neutrino luminosity and jet power, especially with strong magnetic fields, advancing understanding of GRB central engines.

Findings

Neutron star disks have higher neutrino luminosity than black hole disks at the same accretion rate.

Strong magnetic fields increase disk density, temperature, and neutrino luminosity.

Neutrino annihilation and magnetic mechanisms can jointly produce ultra-relativistic jets.

Abstract

Hyperaccreting disks around neutron stars or magnetars cooled via neutrino emission can be the potential central engine of GRBs. The neutron-star disk can cool more efficiently, produce much higher neutrino luminosity and neutrino annihilation luminosity than its black hole counterpart with the same accretion rate. The neutron star surface boundary layer could increase the annihilation luminosity as well. An ultra relativistic jet via neutrino annihilation can be produced along the stellar poles. Moreover, we investigate the effects of strong fields on the disks around magnetars. In general, stronger fields give higher disk densities, pressures, temperatures and neutrino luminosity; the neutrino annihilation mechanism and the magnetically-driven pulsar wind which extracts the stellar rotational energy can work together to generate and feed an even stronger ultra-relativistic jet along the stellar magnetic poles.