Superfluid phase transition and effects of pairing fluctuations in neutron star matter at subnuclear densities

We investigate the s-wave superfluidity in asymmetric nuclear matter in the inner crust and the outer core of the neutron stars. Within the framework of diagrammatic strong coupling theory, which can successfully describe the Bardeen-Cooper-Schrieffer-Bose-Einstein-condensation (BCS-BEC) crossover realized in ultracold Fermi atomic gases, we clarify effects of strong pairing fluctuations on the critical temperature of the superfluid phase transition under the presence of the effective-range correction and the short-range repulsion for the neutron-neutron interaction. Furthermore, considering a finite proton fraction, we show the effects of the strong neutron-proton interaction on the spin-triplet deuteron condensation, as well as on the spin-singlet dineutron and diproton condensations. Our microscopic study on the superfluidity in neutron star matter is important for understanding the astrophysical observations of the thermal properties of neutron stars.