Symmetry energy and neutron star properties constrained by chiral effective field theory calculations

Abstract

We investigate the nuclear symmetry energy and neutron star properties using a Bayesian analysis based on constraints from different chiral effective field theory calculations using new energy density functionals that allow for large variations at high densities. Constraints at high densities are included from observations of GW170817 and from NICER. In particular, we show that both NICER analyses lead to very similar posterior results for the symmetry energy and neutron star properties when folded into our equation-of-state framework. Using the posteriors, we provide results for the symmetry energy and the slope parameter, as well as for the proton fraction, the speed of sound, and the central density in neutron stars. Moreover, we explore correlations of neutron star radii with the pressure and the speed of sound in neutron stars. Our 95\% credibility ranges for the symmetry energy $S_v$, the slope parameter $L$, and the radius of a 1.4$\msun$ neutron star, $R_{1.4}$, are $S_v=(30.6\text{–}33.9)$\,MeV, $L=(43.7\text{–}70.0)$\,MeV, and $R_{1.4}=(11.6\text{–}13.2)$\,km. Our analysis for the proton fraction shows that larger and/or heavier neutron stars are more likely to cool rapidly via the direct Urca process. Within our equation-of-state framework a maximum mass of neutron stars $M_{\rm max}>2.1\msun$ indicates that the speed of sound needs to exceed the conformal limit.

Published version, 12 pages, 13 figures

References in corpus (21)

• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• PSR J0030+0451 Mass and Radius from NICER Data and Implications for the Properties of Neutron Star Matter
• A NICER View of PSR J0030+0451: Millisecond Pulsar Parameter Estimation
• Neutron Star Observations: Prognosis for Equation of State Constraints
• A NICER View of the Massive Pulsar PSR J0740+6620 Informed by Radio Timing and XMM-Newton Spectroscopy
• Refined Mass and Geometric Measurements of the High-Mass PSR J0740+6620
• Improved nuclear matter calculations from chiral low-momentum interactions
• Neutron matter at next-to-next-to-next-to-leading order in chiral effective field theory
• Constraining Neutron-Star Matter with Microscopic and Macroscopic Collisions
• Sound velocity bound and neutron stars
• On the Sound Speed in Neutron Stars
• Astrophysical Constraints on the Symmetry Energy and the Neutron Skin of ${}^{208}$Pb with Minimal Modeling Assumptions
• Chiral Effective Field Theory and the High-Density Nuclear Equation of State
• Multimessenger constraints for ultra-dense matter
• Ab-initio QCD calculations impact the inference of the neutron-star-matter equation of state
• New equations of state constrained by nuclear physics, observations, and QCD calculations of high-density nuclear matter
• Combining Electromagnetic and Gravitational-Wave Constraints on Neutron-Star Masses and Radii
• A Detailed Examination of Astrophysical Constraints on the Symmetry Energy and the Neutron Skin of ${}^{208}$Pb with Minimal Modeling Assumptions
• Nuclear equation of state for arbitrary proton fraction and temperature based on chiral effective field theory and a Gaussian process emulator
• Constraints on the nuclear symmetry energy from asymmetric-matter calculations with chiral NN and 3N interactions

Cited by in corpus (10)

• Constraining the dense matter equation of state with new NICER mass-radius measurements and new chiral effective field theory inputs
• A Bayesian mixture model approach to quantifying the empirical nuclear saturation point
• Implications of latest NICER data for the neutron star equation of state
• Comprehensive Analysis of Constructing Hybrid Stars with an RG-consistent NJL Model
• Influence of the effective mass on the properties of nuclear matter at finite density and temperature
• Model-Independent Determination of the Tidal Deformability of a 1.4 $M_{\odot }$ Neutron Star from Gravitational-Wave Measurements
• Equation of State Independent Determination on the Radius of a 1.4 $M_{\odot }$ Neutron Star Using Mass-Radius Measurements
• Effect of Dark matter and $\sigma$-cut potential on radial and non-radial oscillation modes in neutron stars
• Novel features of asymmetric nuclear matter from terrestrial experiments and astrophysical observations of neutron stars
• Exact evaluation of large-charge correlation functions in non-relativistic conformal field theory