Abstract: With recent advances in astronomical observations, major progress has been made in determining the
pressure of neutron star matter at high density. This pressure is constrained by the neutron star deformability,
determined from gravitational waves emitted in a neutron-star merger, and the mass-radii relation of two neutron
stars, determined from a new X-ray observatory on the International Space Station. Previous studies have relied on
nuclear theory calculations to constrain the equation of state at low density. Here we use a combination of constraints composed of three astronomical observations and twelve nuclear experimental constraints that extend over a wide range of densities. A Bayesian inference framework is then used to obtain a comprehensive nuclear equation of state. This data-centric result provides benchmarks for theoretical calculations and modeling of nuclear matter and neutron stars. Furthermore, it provides insights into the microscopic degrees of freedom of the nuclear matter equation of state and on the composition of neutron stars and their cooling via neutrino radiation.
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Neutron Stars and the Nuclear Matter Equation of State
Neutron stars provide a window into the properties of dense nuclear matter. Several recent observational and theoretical developments provide powerful constraints on their structure and internal composition. Among these are the first observed binary neutron star merger, GW170817, whose gravitational radiation was accompanied by electromagnetic radiation from a short γ-ray burst and an optical afterglow believed to be due to the radioactive decay of newly minted heavy r-process nuclei. These observations give important constraints on the radii of typical neutron stars and on the upper limit to the neutron star maximum mass and complement recent pulsar observations that established a lower limit. Pulse-profile observations by the Neutron Star Interior Composition Explorer (NICER) X-ray telescope provide an independent, consistent measure of the neutron star radius. Theoretical many-body studies of neutron matter reinforce these estimates of neutron star radii. Studies using parameterized dense matter equations of state (EOSs) reveal several EOS-independent relations connecting global neutron star properties.
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- PAR ID:
- 10330279
- Date Published:
- Journal Name:
- Annual Review of Nuclear and Particle Science
- Volume:
- 71
- Issue:
- 1
- ISSN:
- 0163-8998
- Page Range / eLocation ID:
- 433 to 464
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1146/annurev-nucl-102419-124827
