How Well Do We Know the NeutronMatter Equation of State at the Densities Inside Neutron Stars? A Bayesian Approach with Correlated Uncertainties
Abstract
We introduce a new framework for quantifying correlated uncertainties of the infinitematter equation of state derived from chiral effective field theory (χ EFT ). Bayesian machine learning via Gaussian processes with physicsbased hyperparameters allows us to efficiently quantify and propagate theoretical uncertainties of the equation of state, such as χ EFT truncation errors, to derived quantities. We apply this framework to stateoftheart manybody perturbation theory calculations with nucleonnucleon and threenucleon interactions up to fourth order in the χ EFT expansion. This produces the first statistically robust uncertainty estimates for key quantities of neutron stars. We give results up to twice nuclear saturation density for the energy per particle, pressure, and speed of sound of neutron matter, as well as for the nuclear symmetry energy and its derivative. At nuclear saturation density, the predicted symmetry energy and its slope are consistent with experimental constraints.
 Publication:

Physical Review Letters
 Pub Date:
 November 2020
 DOI:
 10.1103/PhysRevLett.125.202702
 arXiv:
 arXiv:2004.07232
 Bibcode:
 2020PhRvL.125t2702D
 Keywords:

 Nuclear Theory;
 Astrophysics  High Energy Astrophysical Phenomena;
 High Energy Physics  Phenomenology;
 Nuclear Experiment
 EPrint:
 7 pages, 2 figures, supplemental material