Properties of a quantum vortex in neutron matter

We have studied systematically various microscopic properties of a quantum vortex in neutron matter at different temperatures and densities corresponding to different layers of the inner crust of a neutron star. To this end, we have carried out fully self-consistent 3D Hartree-Fock-Bogoliubov calculations, using one of the latest nuclear energy-density functionals from the Brussels-Montreal family, which has been developed specifically for applications to neutron superfluidity in neutron-star crusts. By analyzing the flow around the vortex, we have determined the effective radius relevant for the vortex filament model. We have also calculated the specific heat in the presence of the quantum vortex and have shown that it is substantially larger than for a uniform system at low temperatures. We have identified the low temperature limit of the specific heat as being determined by Andreev states inside the vortex core. The typical energy scale associated with Andreev states is defined by the minigap, which we have extracted for various neutron-matter densities. Our results suggest that vortices may be spin-polarized in the crust of magnetars. Finally, we have discussed how to evaluate the specific heat for an arbitrary surface density of vortices, taking into account both the contributions from the vortex core states and from the hydrodynamic flow.