The nuclear matter density functional under the nucleonic hypothesis

TL;DR

This paper uses Bayesian analysis of recent astrophysical data to support the hypothesis that dense matter in neutron stars is composed solely of nucleons, providing a baseline for future searches for exotic matter.

Contribution

It presents the most general behavior of dense matter properties consistent with current observations under the nucleonic hypothesis.

Findings

Observations are compatible with a purely nucleonic composition.

Derived the general behavior of symmetry energy and energy per particle.

Provides a null hypothesis for future dense matter studies.

Abstract

A Bayesian analysis of the possible behaviors of the dense matter equation of state informed through recent LIGO-Virgo as well as NICER measurements reveals that all the present observations are compatible with a fully nucleonic hypothesis for the composition of dense matter, even in the core of the most massive pulsar PSR J0740+6620. Under the hypothesis of a nucleonic composition, we extract the most general behavior of the energy per particle of symmetric matter and density dependence of the symmetry energy, compatible with the astrophysical observations as well as our present knowledge of low energy nuclear physics from effective field theory predictions and experimental nuclear mass data. These results can be used as a null hypothesis to be confronted with future constraints on dense matter to search for possible exotic degrees of freedom.