Implementation of a model of the neutron star crust with a consistent determination of bulk and surface energies.

Neutron stars are remnants of supernova that typically have a

gravitational pull up to 10¹² m/s². Due to this gravitational pull, the

mass of the neutron star (comparable to that of our sun), is compressed

into an object with a radius of approximately 10 kilometers. Thus,

neutron stars consist of the densest matter in the known universe,

making them optimal for studying fundamental forces in extreme

environments. Neutron stars have a solid crust made of nuclei arranged

in a crystalline structure and a liquid core comprised primarily of

neutrons. Of particular interest is the inner crust which has neutrons

external to the nuclei in the lattice. In order to describe matter here,

one uses the Compressible Liquid-Drop Model (CLDM) which models the

nuclei and neutrons as uniform density nuclear matter separated by a

nuclear surface with a certain surface energy which must be specified

independently. In this work, we implement a method to determine the

surface energy consistently with the bulk energy of nuclear matter. We

take different models of nuclear matter characterized by different

values of the symmetry energy - the energy cost of adding neutrons to

the system - and fit the surface energy parameters in the CLDM to

measurements of nuclear masses. We then use this to assess the

importance of such a consistent calculation for the accurate inference

of properties of the neutron star crust from experimental and

astrophysical data.