Probing nuclear superfluidity with neutron stars

Nicolas Chamel (Institute of Astronomy and Astrophysics, Université Libre de Bruxelles, Belgium)

Formed in the furnace of gravitational core-collapse supernova explosions, neutron stars contain matter crushed at densities exceeding that found inside the heaviest atomic nuclei. With typical temperatures of order ten million degrees, the highly degenerate matter in neutron stars is expected to become cold enough for the appearance of superfluids and superconductors – frictionless quantum liquids respectively electrically neutral and charged – made of neutrons and protons, and more speculatively of other particles such as hyperons or quarks. If these phase transitions really occur, neutron stars would not only be the largest superfluid and superconducting systems known in the Universe, but also the hottest ones with critical temperatures reaching ten billion degrees.

After describing the main properties of terrestrial superfluids and superconductors, our current understanding of analogous phenomena in neutron stars will be reviewed together with their astrophysical manifestations.