Equation of state of dense nuclear matter and neutron star structure from nuclear chiral interactions

TL;DR

This paper develops a new microscopic equation of state for dense nuclear matter using chiral interactions, and applies it to compute neutron star properties consistent with observational data.

Contribution

It introduces a chiral effective field theory-based EOS including the $ riangle(1232)$ isobar, suitable for neutron star simulations and consistent with experimental and observational constraints.

Findings

EOS reproduces empirical saturation point and symmetry energy

EOS compatible with heavy-ion collision data up to 4 times saturation density

Neutron star models match observed masses, including 2.01 solar masses

Abstract

We report a new microscopic equation of state (EOS) of dense symmetric nuclear matter, pure neutron matter, and asymmetric and $\beta$-stable nuclear matter at zero temperature using recent realistic two-body and three-body nuclear interactions derived in the framework of chiral perturbation theory (ChPT) and including the $\Delta(1232)$ isobar intermediate state. This EOS is provided in tabular form and in parametrized form ready for use in numerical general relativity simulations of binary neutron star merging. Here we use our new EOS for $\beta$-stable nuclear matter to compute various structural properties of non-rotating neutron stars.The EOS is derived using the Brueckner--Bethe--Goldstone quantum many-body theory in the Brueckner--Hartree--Fock approximation. Neutron star properties are next computed solving numerically the Tolman--Oppenheimer--Volkov structure equations. Our EOS models are able to reproduce the empirical saturation point of symmetric nuclear matter, the symmetry energy $E_{sym}$, and its slope parameter $L$ at the empirical saturation density $n_{0}$. In addition, our EOS models are compatible with experimental data from collisions between heavy nuclei at energies ranging from a few tens of MeV up to several hundreds of MeV per nucleon. These experiments provide a selective test for constraining the nuclear EOS up to $\sim 4 n_0$. Our EOS models are consistent with present measured neutron star masses and particularly with the mass $M = 2.01 \pm 0.04 \, M_{\odot}$ of the neutron stars in PSR~J0348+0432.