Constructing an Equation of State from Pure Neutron Matter Calculations

The equation of state (EoS) for dense, beta-equilibrated nuclear matter is a fundamental ingredient for simulations of binary neutron star mergers, calculation of cooling curves, and other transport properties. We construct a new EoS using a relativistic-mean-field theory (RMF). Typically, the couplings in an RMF are fit to isospin-symmetric nuclear matter data, but the matter in neutron stars is much closer in composition to pure neutron matter. In this work, along with reproducing isospin-symmetric nuclear matter data, we also fit our RMF to pure neutron matter calculations from chiral effective field theory. These calculations are needed because it is not possible to perform experiments on pure neutron matter on Earth. Our EoS agrees with current mass and radius measurements from NICER and LIGO.