New magnetic field instability and magnetar bursts

TL;DR

This paper investigates how electrons with anomalous magnetic moments in neutron-rich environments can induce magnetic field instabilities, potentially explaining magnetar bursts through magnetic field amplification.

Contribution

It provides an exact solution to the Dirac equation for such electrons and demonstrates magnetic field instability leading to significant amplification in neutron star conditions.

Findings

Nonzero electric current flows along magnetic fields due to anomalous magnetic moments.

Magnetic field instability can amplify seed fields by over an order of magnitude.

Results may explain electromagnetic bursts observed in magnetars.

Abstract

We consider the system of massive electrons, possessing nonzero anomalous magnetic moments, which electroweakly interact with background neutrons under the influence of an external magnetic field. The Dirac equation for such electrons is exactly solved. Basing on the obtained solution, we find that a nonzero electric current of these electrons can flow along the magnetic field. Accounting for the new current in the Maxwell equations, we demonstrate that a magnetic field in this system appears to be unstable. Then we consider a particular case of a degenerate electron gas, which may well exist in a neutron star, and show that a seed magnetic field can be amplified by more than one order of magnitude. Finally we discuss the application of our results for the explanation of the electromagnetic radiation emitted by magnetars.