Superfluid fraction in the slab phase of the inner crust of neutron stars

Abstract

An analysis of the slab phase as it is expected in the innermost layer of neutron-star crusts is performed within the Hartree-Fock-Bogoliubov framework. We take the periodicity of the slabs into account using Bloch boundary conditions, in order to well describe the interplay between the band structure and superfluidity. We introduce a relative flow between the slabs and the surrounding neutron gas in a time-independent way. This induces a non-trivial phase of the complex order parameter, leading to a counterflow between neutrons inside and outside the slabs. With the resulting current, we compute the actual neutron superfluid fraction. For the latter our results are slightly larger than previous ones obtained in normal band theory, suggesting that normal band theory overestimates the entrainment effect.