General Relativistic Considerations of the Field Shedding Model of Fast Radio Bursts

TL;DR

This paper explores the relativistic physics of magnetic flux shedding during neutron star collapse into black holes, proposing a model that accounts for angular momentum and charge, and discusses its implications for fast radio burst origins.

Contribution

It introduces a fully relativistic Kerr-Newman black hole model for magnetic flux shedding in FRB progenitors, extending previous simpler models based on Schwarzschild metrics.

Findings

Magnetic flux shedding is plausible for neutron stars with long periods and high magnetic fields.

The model accounts for electric discharge in a metastable black hole state.

Observational evidence supports the relevance of magnetic flux shedding in FRB production.

Abstract

Popular models of fast radio bursts (FRBs) involve the gravitational collapse of neutron star progenitors to black holes. It has been proposed that the shedding of the strong neutron star magnetic field ($B$) during the collapse is the power source for the radio emission. Previously, these models have utilized the simplicity of the Schwarzschild metric which has the restriction that the magnetic flux is magnetic "hair" that must be shed before final collapse. But, neutron stars have angular momentum and charge and a fully relativistic Kerr Newman solution exists in which $B$ has its source inside of the event horizon. In this letter, we consider the magnetic flux to be shed as a consequence of the electric discharge of a metastable collapsed state of a Kerr Newman black hole. It has also been argued that the shedding model will not operate due to pair creation. By considering the pulsar death line, we find that for a neutron star with $B = 10^{11} - 10^{13}$ G and a long rotation period, $>1$ s this is not a concern. We also discuss the observational evidence supporting the plausibility of magnetic flux shedding models of FRBs that are spawned from rapidly rotating progenitors.