Neutron specific heat in the crust of neutron stars from the nuclear band theory

TL;DR

This paper calculates the neutron specific heat in the crust of neutron stars using nuclear band theory, revealing that unbound neutrons behave like a Fermi gas despite lattice effects, due to their Fermi surface properties.

Contribution

It applies the band theory of solids to neutron star crusts and tests various approximations, providing new insights into neutron behavior and specific heat in this extreme environment.

Findings

Neutron specific heat is similar to that of a Fermi gas.

Unbound neutron motion is strongly influenced by the nuclear lattice.

Fermi surface properties explain the apparent contradiction.

Abstract

The inner crust of neutron stars, formed of a crystal lattice of uclear clusters immersed in a sea of unbound neutrons, may be the nique example of periodic nuclear systems. We have calculated the neutron specific heat in the shallow part of the crust using the band theory of solids with Skyrme nucleon-nucleon interactions. We have also tested the validity of various approximations. We have found that the neutron specific heat is well described by that of a Fermi gas, while the motion of the unbound neutrons is strongly affected by the nuclear lattice. These apparently contradictory results are explained by the particular properties of the neutron Fermi surface.