Empirical radius formulas for canonical neutron stars from bidirectionally selecting EOS features in extended Bayesian analyses of observational data

Abstract

Given the significant advancement in Bayesian inference of nuclear Equation of State (EOS) from gravitational wave and X-ray observations of neutron stars (NSs), especially since GW170817, is there a data-driven and robust empirical formula for the radius $R_{1.4}$ of canonical NSs in terms of the characteristic EOS parameters (features)? What is the single most important but currently poorly known EOS parameter for determining the $R_{1.4}$? We study these questions by extending the traditional Bayesian analysis which normally ends at presenting the marginalized posterior probability distribution functions (PDFs) of individual EOS parameters and their correlations (or sometimes only the Pearson correlation coefficients which are only reliably useful when the variables are linearly correlated while they are actually often not). Using three regression model-building methodologies: bidirectional step-wise feature selection, Least Absolute Shrinkage Selection Operator (LASSO) regression, and neural network regression on a large set of posterior EOSs and the corresponding $R_{1.4}$ values inferred from earlier comprehensive Bayesian analyses of NS observational data, we systematically and rigorously develop the most probable $R_{1.4}$ formulas with varying statistical accuracy and technical complexity. The most important EOS parameters for determining $R_{1.4}$ are found consistently in each of the feature/model selection processes to be (in order of decreasing importance): curvature $K_{sym}$, slope $L$, skewness $J_{sym}$ of nuclear symmetry energy, skewness $J_0$, incompressibility $K_0$ of symmetric nuclear matter, and the magnitude $E_{sym}({\rho }_0)$ of symmetry energy at the saturation density ${\rho }_0$ of nuclear matter.

Phys. Rev. C (2023) in press

References in corpus (18)

• 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
• Constraints on the Symmetry Energy Using the Mass-Radius Relation of Neutron Stars
• Progress in Constraining Nuclear Symmetry Energy Using Neutron Star Observables Since GW170817
• Towards Understanding Astrophysical Effects of Nuclear Symmetry Energy
• Dense Nuclear Matter Equation of State from Heavy-Ion Collisions
• Locating the inner edge of neutron star crust using terrestrial nuclear laboratory data
• The nuclear symmetry energy and stability of matter in neutron star
• Bayesian Inference of the Symmetry Energy of Super-Dense Neutron-Rich Matter from Future Radius Measurements of Massive Neutron Stars
• Implications of the mass $M=2.17_{-0.10}^{+0.11}$M${}_{\odot }$ of PSR~J0740+6620 on the Equation of State of Super-Dense Neutron-Rich Nuclear Matter
• Interdependence of different symmetry energy elements
• Constraints on the symmetry energy from observational probes of the neutron star crust
• Nucleonic metamodelling in light of multimessenger, PREX-II and CREX data
• Neutron star mass formula with nuclear saturation parameters for asymmetric nuclear matter
• Impact of Symmetry Energy on Sound Speed and Spinodal Decomposition in Dense Neutron-Rich Matter
• Properties of First-Order Hadron-Quark Phase Transition from Inverting Neutron Star Observables
• Empirical neutron star mass formula based on experimental observables
• Neutron star mass formula with nuclear saturation parameters

Cited by in corpus (13)

• Bayesian Inference of Fine-Features of Nuclear Equation of State from Future Neutron Star Radius Measurements to 0.1km Accuracy
• Impact of The Newly Revised Gravitational Redshift of X-ray Burster GS 1826-24 on The Equation of State of Supradense Neutron-Rich Matter
• Novel Scalings of Neutron Star Properties from Analyzing Dimensionless Tolman--Oppenheimer--Volkoff Equations
• Impact of the nuclear equation of state on the formation of twin stars
• Inferring the Equation of State from Neutron Star Observables via Machine Learning
• Neural Network Emulation of Flow in Heavy-Ion Collisions at Intermediate Energies
• Unraveling Trace Anomaly of Supradense Matter via Neutron Star Compactness Scaling
• Bayesian inference of nuclear incompressibility from collective flow in mid-central Au+Au collisions at 400--1500 MeV/nucleon
• Novel features of asymmetric nuclear matter from terrestrial experiments and astrophysical observations of neutron stars
• Anisotropic pressure effect on central EOS of PSR J0740+6620 in the light of dimensionless TOV equation
• Precise constraint on properties of neutron stars through new universal relations and astronomical observations
• Bayesian Constraints on the Neutron Star Equation of State with a Smooth Hadron-Quark Crossover
• Bayesian Inference of fine-features of dense matter EOS from future high-precision data of neutron star radii