Probing Nuclear Symmetry Energy and its Imprints on Properties of Nuclei, Nuclear Reactions, Neutron Stars and Gravitational Waves

TL;DR

This paper reviews recent progress and open questions in understanding nuclear symmetry energy, its effects on nuclear and astrophysical phenomena, especially neutron stars and gravitational waves, emphasizing high-density behavior.

Contribution

It provides a comprehensive overview of constraints, theoretical relationships, and the impact of symmetry energy on neutron star properties and gravitational waves, highlighting unresolved issues at supra-saturation densities.

Findings

Constraints on symmetry energy near saturation density

Relationship between symmetry energy and nucleon potential

Impact of high-density symmetry energy on neutron star tidal polarizability

Abstract

Significant progress has been made in recent years in constraining nuclear symmetry energy at and below the saturation density of nuclear matter using data from both terrestrial nuclear experiments and astrophysical observations. However, many interesting questions remain to be studied especially at supra-saturation densities. In this lecture note, after a brief summary of the currently available constraints on nuclear symmetry energy near the saturation density we first discuss the relationship between the symmetry energy and the isopin and momentum dependence of the single-nucleon potential in isospin-asymmetric nuclear medium. We then discuss several open issues regarding effects of the tensor force induced neutron-proton short-range correlation (SRC) on nuclear symmetry energy. Finally, as an example of the impacts of nuclear symmetry energy on properties of neutron stars and gravitational waves, we illustrate effects of the high-density symmetry energy on the tidal polarizability of neutron stars in coalescing binaries.