Neutron Star Crust Team:

Abstract: The outer region of a neutron star, called the crust, is predicted to host novel states of matter containing exotic neutron-rich nuclei (which in the inner crust are highly deformed), relativistic electrons, and a superfluid of neutrons. Recently, transiently accreting neutron-star low-mass X-ray binaries have emerged as unique laboratories to study thermal and transport processes in these extreme environments and phases encountered in the crust. During a long period of accretion, years to decades, the crust is heated out of thermal equilibrium with the stellar core. When accretion ends, the subsequent thermal relaxation can, and has been, observed in detail. Modeling these events has been fairly successful, but with the introduction of "fudge parameters" which mask our current ignorance about the interesting physics of heat transport, nuclear reactions, and neutron superfluidity at these fairly extreme densities. It is now timely to bring together a team of X-ray observers, theoretical astrophysicists, and theoretical physicists to interpret and guide observations of thermal relaxation with a view to learn about fundamental processes and phases of matter encountered at these extreme densities.