Force-free and twisted, relativistic neutron star magnetospheres

TL;DR

This paper models the structure of a twisted, axisymmetric, force-free neutron star magnetosphere, revealing how increased current affects field line behavior and spin-down, with implications for magnetar torque variations.

Contribution

It introduces a detailed model of a twisted, axisymmetric, force-free magnetosphere and analyzes the effects of twist and current on magnetic field structure and spin-down behavior.

Findings

More field lines cross the light cylinder with increased current.

The twist cannot exceed approximately ${\pi}/2$, beyond which the field becomes radial.

Implications for magnetar torque variations during outbursts.

Abstract

In this poster we present the structure of an axisymmetric, force-free magnetosphere of a twisted, aligned rotating dipole within a corotating plasma-filled magnetosphere. We explore various profiles for the twist. We find that as the current increases more field lines cross the light cylinder leading to more efficient spin-down. Moreover, we notice that the twist cannot be increased indefinitely and after a finite twist of about ${\pi}/2$ the field becomes approximately radial. This could have implications for torque variations of magnetars related to outbursts.