Neutron Matter from Low to High Density

TL;DR

This paper reviews the properties of neutron matter across a range of densities, highlighting its connections to superfluidity, nuclear physics, and astrophysical phenomena like neutron stars.

Contribution

It provides a comprehensive overview of neutron matter from low to high densities, integrating insights from nuclear physics and astrophysics.

Findings

Neutron matter at low density forms a strongly paired superfluid.

High-density neutron matter influences neutron star mass-radius relations.

Connections between neutron matter properties and astrophysical observations.

Abstract

Neutron matter is an intriguing nuclear system with multiple connections to other areas of physics. Considerable progress has been made over the last two decades in exploring the properties of pure neutron fluids. Here we begin by reviewing work done to explore the behavior of very low density neutron matter, which forms a strongly paired superfluid and is thus similar to cold Fermi atoms, though at energy scales differing by many orders of magnitude. We then increase the density, discussing work that ties the study of neutron matter with the determination of the properties of neutron-rich nuclei and neutron-star crusts. After this, we review the impact neutron matter at even higher densities has on the mass-radius relation of neutron stars, thereby making contact with astrophysical observations.