Hot and Dense Matter Equation of State Probability Distributions for Astrophysical Simulations

TL;DR

This paper develops a probabilistic set of equations of state for hot, dense nuclear matter, incorporating empirical constraints and microscopic theory to improve astrophysical simulations of supernovae and neutron star mergers.

Contribution

It introduces a new ensemble-based model for the nuclear equation of state, integrating empirical data and microscopic calculations, with adjustable parameters for uncertainty quantification.

Findings

Provides a probability distribution of hot dense matter equations of state.

Ensures thermodynamic consistency while fitting experimental and observational data.

Compared with existing equations of state, highlighting differences and uncertainties.

Abstract

We add an ensemble of nuclei to the equation of state for homogeneous nucleonic matter to generate a new set of models suitable for astrophysical simulations of core-collapse supernovae and neutron star mergers. We implement empirical constraints from (i) nuclear mass measurements, (ii) proton-proton scattering phase shifts, and (iii) neutron star observations. Our model is also guided by microscopic many-body theory calculations based on realistic nuclear forces, including the zero-temperature neutron matter equation of state from quantum Monte Carlo simulations and thermal contributions to the free energy from finite-temperature many-body perturbation theory. We ensure that the parameters of our model can be varied while preserving thermodynamic consistency and the connection to experimental or observational data, thus providing a probability distribution of the astrophysical hot and dense matter equation of state. We compare our results with those obtained from other available equations of state. While our probability distributions indeed represent a large number of possible equations of state, we cannot yet claim to have fully explored all of the uncertainties, especially with regard to the structure of nuclei in the hot and dense medium.