Neutron conduction in the inner crust of a neutron star in the framework of the band theory of solids

TL;DR

This paper applies the band theory of solids to the inner crust of neutron stars, revealing that the density of conduction neutrons is significantly lower than unbound neutrons due to Bragg scattering, impacting neutron star models.

Contribution

It introduces a solid-state physics approach to quantify conduction neutron density in neutron star crusts, highlighting the importance of Bragg scattering effects.

Findings

Conduction neutron density can be an order of magnitude lower than unbound neutron density.

Bragg scattering significantly affects neutron conduction properties.

Results may lead to revised interpretations of neutron star phenomena.

Abstract

Even though the "free" neutrons in the inner crust of a neutron star are superfluid, they are still strongly coupled to nuclei due to non-dissipative entrainment effects. These effects have been systematically studied in all regions of the inner crust in the framework of the band theory of solids. Using concepts from solid-state physics, it is shown that the density of conduction neutrons, i.e. neutrons that are effectively "free", can be much smaller than the density of unbound neutrons (by an order of magnitude in some layers) due to Bragg scattering. These results suggest that a revision of the interpretation of various observable neutron-star phenomena may be necessary.