Neutron star tidal deformabilities constrained by nuclear theory and experiment

TL;DR

This study combines nuclear theory, laboratory measurements, and gravitational wave data to constrain neutron star properties, revealing that current models are consistent with observations and highlighting the importance of tidal deformability in understanding dense matter.

Contribution

We develop a Bayesian framework integrating nuclear experiments and chiral effective field theory to constrain neutron star equations of state from crust to core.

Findings

Predicted neutron star tidal deformabilities are consistent with GW170817 bounds.

Lower bounds on deformability will strongly constrain dense matter models.

Strong correlation between tidal deformability and pressure at twice saturation density.

Abstract

We confront observational data from gravitational wave event GW170817 with microscopic modeling of the cold neutron star equation of state. We develop and employ a Bayesian statistical framework that enables us to implement constraints on the equation of state from laboratory measurements of nuclei and state-of-the-art chiral effective field theory methods. The energy density functionals constructed from the posterior probability distributions are then used to compute consistently the neutron star equation of state from the outer crust to the inner core, assuming a composition consisting of protons, neutrons, electrons, and muons. In contrast to previous studies, we find that the 95% credibility range of predicted neutron star tidal deformabilities ($136 < \Lambda < 519$) for a 1.4 solar-mass neutron star is already consistent with the upper bound deduced from observations of the GW170817 event. However, we find that lower bounds on the neutron star tidal deformability will very strongly constrain microscopic models of the dense matter equation of state. We also demonstrate a strong correlation between the neutron star tidal deformability and the pressure of beta-equilibrated matter at twice saturation density.