On the superfluid properties of the inner crust of neutron stars

We investigated the superfluid properties of the inner crust of neutron stars, solving the Hartree-Fock-Bogoliubov equations in spherical Wigner-Seitz cells. Using realistic two-body interactions in the pairing channel, we studied in detail the Cooper-pair and the pairing-field spatial properties, together with the effect of the proton clusters on the neutron pairing gap. Calculations with effective pairing interactions are also presented, showing significant discrepancies with the results obtained with realistic pairing forces. At variance with recent studies on finite nuclei, the neutron coherence length is found to depend on the strength of the pairing interaction, even inside the nucleus. We also show that the Wigner-Seitz approximation breaks down in the innermost regions of the inner crust, already at baryonic densities $ρ_b \ge 8 \cdot 10^{+13}$ g $\cdot$ cm$^{-3}$.