Magnetic fields in superconducting neutron stars

TL;DR

This paper develops a model for magnetic fields in superconducting neutron stars, presenting the first self-consistent equilibria with mixed magnetic field configurations and analyzing their structural distortions.

Contribution

It introduces a differential equation governing magnetic fields in superconducting neutron stars and provides the first self-consistent solutions with poloidal and mixed fields.

Findings

Poloidal magnetic fields dominate in the configurations.

Superconducting matter causes significant magnetic field rearrangement.

Magnetic field-induced distortions are quantitatively characterized.

Abstract

The interior of a neutron star is likely to be predominantly a mixture of superfluid neutrons and superconducting protons. This results in the quantisation of the star's magnetic field into an array of thin fluxtubes, producing a macroscopic force very different from the Lorentz force of normal matter. We show that in an axisymmetric superconducting equilibrium the behaviour of a magnetic field is governed by a single differential equation. Solving this, we present the first self-consistent superconducting neutron star equilibria with poloidal and mixed poloidal-toroidal fields, also giving the first quantitative results for the corresponding magnetically-induced distortions to the star. The poloidal component is dominant in all our configurations. We suggest that the transition from normal to superconducting matter in a young neutron star may cause a large-scale field rearrangement.