Neutron matter at finite temperature based on chiral effective field theory interactions

TL;DR

This paper calculates the thermodynamic properties of neutron matter at finite temperature using chiral effective field theory interactions, including three-nucleon forces, and assesses uncertainties to inform astrophysical models.

Contribution

It introduces a comprehensive framework for neutron matter at finite temperature with explicit three-nucleon interactions and uncertainty quantification, advancing previous zero-temperature studies.

Findings

Thermal effects are well described by a thermal index and effective mass.

The approach accurately captures the equation of state relevant for astrophysical phenomena.

Uncertainty estimates are provided based on chiral expansion order-by-order analysis.

Abstract

We study the equation of state of neutron matter at finite temperature based on two- and three-nucleon interactions derived within chiral effective field theory to next-to-next-to-next-to-leading order. The free energy, pressure, entropy, and internal energy are calculated using many-body perturbation theory including terms up to third order around the self-consistent Hartree-Fock solution. We include contributions from three-nucleon interactions without employing the normal-ordering approximation and provide theoretical uncertainty estimates based on an order-by-order analysis in the chiral expansion. Our results demonstrate that thermal effects can be captured remarkably well via a thermal index and a density-dependent effective mass. The presented framework provides the basis for studying the dense matter equation of state at general temperatures and proton fractions relevant for core-collapse supernovae and neutron star mergers.