We summarize our current knowledge of neutron-star masses and radii. Recent instrumentation and computational advances have resulted in a rapid increase in the discovery rate and precise timing of radio pulsars in binaries in the past few years, leading to a large number of mass measurements. These discoveries show that the neutron-star mass distribution is much wider than previously thought, with three known pulsars now firmly in the 1.9-2.0-M☉ mass range. For radii, large, high-quality data sets from X-ray satellites as well as significant progress in theoretical modeling led to considerable progress in the measurements, placing them in the 10-11.5-km range and shrinking their uncertainties, owing to a better understanding of the sources of systematic errors. The combination of the massive-neutron-star discoveries, the tighter radius measurements, and improved laboratory constraints of the properties of dense matter has already made a substantial impact on our understanding of the composition and bulk properties of cold nuclear matter at densities higher than that of the atomic nucleus, a major unsolved problem in modern physics.
Annual Review of Astronomy and Astrophysics
- Pub Date:
- September 2016
- Astrophysics - High Energy Astrophysical Phenomena;
- General Relativity and Quantum Cosmology;
- Nuclear Theory
- To be published in Annual Reviews of Astronomy and Astrophysics 2016. All mass, radius, and equation of state data are available at http://xtreme.as.arizona.edu/NeutronStars