General features of the stellar matter equation of state from microscopic theory, new maximum-mass constraints, and causality

TL;DR

This paper emphasizes the importance of using microscopic ab initio theories as baselines for modeling neutron star matter, applying causality and maximum-mass constraints to derive reliable high-density equations of state and neutron star predictions.

Contribution

It introduces a methodology combining microscopic theories with phenomenological extensions guided by causality and speed of sound constraints for neutron star modeling.

Findings

Derived new neutron star maximum mass constraints.

Predicted neutron star cooling curves consistent with observations.

Established bounds on high-density equations of state.

Abstract

The profile of a neutron star probes a very large range of densities, from the density of iron up to several times the density of saturated nuclear matter, and thus no theory of hadrons can be considered reliable if extended to those regions. We emphasize the importance of taking contemporary ab initio theories of nuclear and neutron matter as the baseline for any extension method, which will unavoidably involve some degree of phenomenology. We discuss how microscopic theory, on the one end, with causality and maximum-mass constraints, on the other, set strong boundaries to the high-density equation of state. We present our latest neutron star predictions where we combine polytropic extensions and parametrizations guided by speed of sound considerations. The predictions we show include our baseline neutron star cooling curves.