Properties of the outer crust of neutron stars from Hartree-Fock-Bogoliubov mass models

Abstract

We have calculated the zero-temperature properties of the outer crust of neutron stars for four nuclear-mass models based on the Hartree-Fock-Bogoliubov method: the three most recent Skyrme-force models (HFB-19, HFB-20, and HFB-21) and the Gogny-force model D1M. While the equation of state is substantially the same for the four models, the nuclidic composition varies considerably from one model to another. We solve the Tolman-Oppenheimer-Volkoff equations by integrating inward from the surface and thereby determine the abundance of each nuclide in the outer crust of a typical neutron star of mass $1.5{M}_{\ensuremath{\bigodot}}$ and radius 13 km. Although the total mass of the outer crust is slightly model dependent, its thickness is essentially the same for all four models.