Proton superconductivity in pasta phases in neutron star crusts

TL;DR

This paper investigates proton superconductivity in neutron star crust pasta phases, especially the lasagna phase, predicting Type II superconductivity with anisotropic flux lines and discussing implications for magnetic and electrical properties in astrophysical contexts.

Contribution

It introduces the concept of proton superconductivity in pasta phases, providing detailed magnetic property analysis and flux line energy calculations, which are novel in neutron star crust studies.

Findings

Pasta phases can exhibit proton superconductivity.

Flux lines are strongly anisotropic in these phases.

Imperfect pasta structures may lead to flux pinning and long flux decay times.

Abstract

In the so-called pasta phases predicted to occur in neutron star crusts, protons are able to move easily over large distances because the nuclear matter regions are extended in space. Consequently, electrical currents can be carried by protons, an effect not possible in conventional crystalline matter with isolated nuclei. With emphasis on the so-called lasagna phase, which has sheet-like nuclei, we describe the magnetic properties of the pasta phases allowing for proton superconductivity. We predict that these phases will be Type II superconductors and we calculate the energy per unit length of a flux line, which is shown to be strongly anisotropic. If, as seems likely, the pasta structure is imperfect, flux lines will be pinned and matter will behave as a good electrical conductor and flux decay times will be long. We describe some possible astrophysical manifestations of our results.