Realistic energies for vortex pinning in intermediate-density neutron star matter

Realistic values for the pinning energies of vortices in the neutron superfluid expected in the inner crust of neutron stars are crucial for the theory of pulsar glitches. To this end, we supplement our consistent semi-classical model for the vortex-nucleus interaction with general properties of intermediate-density fermion systems with large negative scattering lengths, such as neutron matter at the densities corresponding to the inner crust. We also implement the reduction of pairing expected from the polarization of the strongly correlated neutron medium, although allowing for the present large theoretical uncertainties on the amount of reduction. Finally, we better evaluate the kinetic contributions to pinning accounting also for the quantum structure of the vortex core, which sustains divergenceless flow. When compared to existing results, we find weaker values for the pinning energies per site (EP<3.5MeV); moreover, significant nuclear pinning occurs only in a restricted density range (about 2×1013≲ρ≲5×1013g/cm3 or 0.07ρ0≲ρ≲0.2ρ0, with ρ0 the nuclear saturation density). The rest of the crust presents either interstitial pinning (ρ<0.07ρ0) or collective super-weak pinning (ρ>0.2ρ0), both negligible at the macroscopic scale relevant to vortex unpinning and glitches.