Low-energy nuclear physics and global neutron star properties

TL;DR

This paper investigates how low-energy nuclear physics data constrains neutron star properties, finding that symmetry energy constraints are most effective, but uncertainties in high-density behavior remain significant.

Contribution

It systematically assesses nuclear interactions' ability to reproduce nuclear data and links these to neutron star property predictions, highlighting the impact of symmetry energy constraints.

Findings

Neutron star radius for 1.4 solar masses is between 12 and 14 km.

Symmetry energy and its slope are tightly correlated and constrained.

Uncertainties in high-density behavior dominate neutron star property predictions.

Abstract

We address the question of the role of low-energy nuclear physics data in constraining neutron star global properties, e.g., masses, radii, angular momentum, and tidal deformability, in the absence of a phase transition in dense matter. To do so, we assess the capacity of 415 relativistic mean field and non-relativistic Skyrme-type interactions to reproduce the ground state binding energies, the charge radii and the giant monopole resonances of a set of spherical nuclei. The interactions are classified according to their ability to describe these characteristics and we show that a tight correlation between the symmetry energy and its slope is obtained providing $N=Z$ and $N\ne Z$ nuclei are described with the same accuracy (mainly driven by the charge radius data). By additionally imposing the constraints from isobaric analog states and neutron skin radius in $^{208}$Pb, we obtain the following estimates: $E_{sym,2}=31.8\pm 0.7$ MeV and $L_{sym,2}=58.1\pm 9.0$ MeV. We then analyze predictions of neutron star properties and we find that the 1.4$M_\odot$ neutron star (NS) radius lies between 12 and 14 km for the "better" nuclear interactions. We show that i) the better reproduction of low-energy nuclear physics data by the nuclear models only weakly impacts the global properties of canonical mass neutron stars and ii) the experimental constraint on the symmetry energy is the most effective one for reducing the uncertainties in NS matter. However, since the density region where constraints are required are well above densities in finite nuclei, the largest uncertainty originates from the density dependence of the EDF, which remains largely unknown.