Unified equations of state of neutron stars

Born from the catastrophic gravitational core collapse of massive stars during type II supernova explosions, neutron stars are among the most compact objects in the Universe. With a mass of the order of that of the Sun compressed inside a radius of only 10 km or so their central density can exceed several times that found inside heavy atomic nuclei. 

Despite their names, neutron stars are not only made of neutrons. They are likely to be surrounded by a thin atmosphere, a few centimeter thick at most, hindering a metallic surface composed mainly of iron. The outermost layers of an isolated neutron star at densities above ten thousand grams per cubic centimeters consists of a solid crust composed of fully ionized atomic nuclei arranged in a Coulomb lattice and coexisting with a quantum gas of electrons. The composition of these layers is almost completely determined  by experimental atomic masses. Deeper in the star, nuclei become so neutron-rich that neutrons drip out of nuclei forming an underground neutron superfluid. The crust dissolves into a uniform liquid of neutrons, protons and electrons when the density reaches about half that found inside heavy atomic nuclei. 

A unified description of all regions of a neutron star will be presented. Our approach is based on the nuclear energy density functional theory with generalized Skyrme functionals that were simultaneously fitted to essentially all measured nuclear masses (with a rms deviation of 0.58 MeV) and to one or other of three different equations of state of pure neutron matter, each determined by a different many-body calculation using realistic two- and three-body interactions.  Predictions for the global structure of a neutron star will be compared with astrophysical observations.