Cooling of Superuid Neutron Stars

Cooling of neutron stars (NSs) with the cores composed of neutrons, protons, and electrons is analyzed. The main cooling regulators are discussed: opening of direct Urca process in a NS central kernel; superuidity of nucleons in NS interiors; surface layers of light (accreted) elements; strong surface magnetic elds. An emphasis is paid on the cooling scenario with strong S 0 pairing of protons and weak P 2 pairing of neutrons in the NS core, as well as strong S 0 pairing of neutrons in the NS crust. The theory predicts three types of isolated cooling middle-aged NSs with distinctly dierent properties: low-mass, slowly cooling NSs; medium-mass, moderately cooling NSs; massive, rapidly cooling NSs. The theory is compared with observations of isolated NSs | pulsars and radio quiet NSs in supernova remnants. The constraints on physical properties of NSs which can be inferred from such a comparison are outlined