Masses of neutron stars and nuclei

TL;DR

This paper calculates maximum neutron star masses using Skyrme functionals fitted to nuclear mass data and neutron matter equations of state, showing observational data favor the stiffest model BSk21.

Contribution

It introduces new constraints on neutron star models by combining nuclear mass data with different neutron matter equations of state, favoring the stiffest functional BSk21.

Findings

Observation of a 1.97 solar mass neutron star rules out the softest model BSk19.

Nuclear mass measurements support the stiffest model BSk21.

The models fit nuclear data with 0.58 MeV rms deviation.

Abstract

We calculate the maximum mass of neutron stars for three different equations of state (EOS) based on generalized Skyrme functionals that are simultaneously fitted to essentially all the 2003 nuclear mass data (the rms deviation is 0.58 MeV in all three cases) 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 but leading to significantly different degrees of stiffness at the high densities prevailing in neutron-star interiors. The observation of a neutron star with mass 1.97 $\pm$ 0.04 $\mathcal{M}_{\odot}$ eliminates the softest of our models (BSk19), but does not discriminate between BSk20 and BSk21. However, nuclear-mass measurements that have been made since our models were constructed strongly favor BSk21, our stiffest functional.