Neutron star crust and outer core equation of state from chiral effective field theory with quantified uncertainties

Abstract

We study the order-by-order expansion of the energy per particle of asymmetric nuclear matter up to twice saturation density in chiral effective field theory (EFT) within a Bayesian framework. For this, we develop a two-dimensional Gaussian process (2D GP) that is trained using many-body perturbation theory results based on chiral two- and three-nucleon interactions from leading to next-to-next-to-next-to-leading order (N${}^3$LO). This allows for an efficient evaluation of the equation of state (EOS) and thermodynamic derivatives with EFT truncation uncertainties. After benchmarking our 2D GP against Bayesian uncertainties for pure neutron matter and symmetric matter, we study the energy per particle, pressure, and chemical potentials of neutron star matter in $\beta$-equilibrium including EFT uncertainties. We investigate the phase diagram of neutron-rich matter from neutron- to proton-drip and to the uniform phase, including surface and Coulomb corrections. Based on this, we construct EOSs for the inner crust of neutron stars that are consistent with the chiral EFT results for uniform matter at N${}^3$LO.

14 pages, 15 figures, published version

References in corpus (12)

• Chiral effective field theory and nuclear forces
• Neutron matter at next-to-next-to-next-to-leading order in chiral effective field theory
• Constraining the dense matter equation of state with new NICER mass-radius measurements and new chiral effective field theory inputs
• Nuclear equation of state for arbitrary proton fraction and temperature based on chiral effective field theory and a Gaussian process emulator
• The Neutron Star Crust: Nuclear Physics Input
• Spectrum of shear modes in the neutron-star crust: Estimating the nuclear-physics uncertainties
• Neutron stars and the dense matter equation of state: from microscopic theory to macroscopic observations
• Diagrammatic ab initio methods for infinite nuclear matter with modern chiral interactions
• Neutron matter from local chiral effective field theory interactions at large cutoffs
• Effects of nuclear matter properties in neutron star mergers
• Neutron star matter as a dilute solution of protons in neutrons
• Bayesian approach for many-body uncertainties in nuclear structure: Many-body perturbation theory for finite nuclei