Fluxtube Dynamics in Neutron Star Cores

TL;DR

This paper investigates how superconducting proton fluxtubes in neutron star cores influence magnetic field evolution, estimating variable timescales for different densities that could impact observable magnetic phenomena.

Contribution

It provides a detailed analysis of fluxtube dynamics and their role in magnetic field evolution within neutron star cores, considering realistic equations of state.

Findings

Magnetic field evolution timescales vary with density inside the star.

Timescales are shortest near the crust-core interface.

Fluxtube motion significantly affects neutron star magnetism.

Abstract

Although the detailed structure of neutron stars remains unknown, their equilibrium temperatures lie well below the Fermi temperature of dense nuclear matter, suggesting that the nucleons in the stars' core form Cooper pairs and exhibit macroscopic quantum behavior. The presence of such condensates impacts on the neutron stars' large scale properties. Specifically, superconducting protons in the outer core (expected to show type-II properties) alter the stars' magnetism as the magnetic field is no longer locked to the charged plasma but instead confined to fluxtubes. The motion of these structures governs the dynamics of the core magnetic field. To examine if field evolution could be driven on observable timescales, several mechanisms affecting the fluxtube distribution are addressed and characteristic timescales for realistic equations of state estimated. The results suggest that the corresponding timescales are not constant but vary for different densities inside the star, generally being shortest close to the crust-core interface.