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Neutron star properties depend on both nuclear physics and astrophysical processes, and thus observations of neutron stars offer constraints on both large-scale astrophysics and the behavior of cold, dense matter. In this study, we use astronomical data to jointly infer the universal equation of state of dense matter along with two distinct astrophysical populations: Galactic neutron stars observed electromagnetically and merging neutron stars in binaries observed with gravitational waves. We place constraints on neutron star properties and quantify the extent to which they are attributable to macrophysics or microphysics. We confirm previous results indicating that the Galactic and merging neutron stars have distinct mass distributions. The inferred maximum mass of both Galactic neutron stars, πpop,EM=2.0β’5+0.11β0.06β’πβ (median and 90% symmetric credible interval), and merging neutron star binaries, πpop,GW =1.8β’5+0.39β0.16β’πβ, are consistent with the maximum mass of nonrotating neutron stars set by nuclear physics, πTOV =2.2β’8+0.41β0.21β’πβ. The radius of a 1.4β’πβ neutron star is 12.2+0.8β0.9ββkm, consistent with, though βΌ20% tighter than, previous results using an identical equation of state model. Even though observed Galactic and merging neutron stars originate from populations with distinct properties, there is currently no evidence that astrophysical processes cannot produce neutron stars up to the maximum value imposed by nuclear physics.
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Determination of the equation of state from nuclear experiments and neutron star observations
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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- Award ID(s):
- 2209145
- PAR ID:
- 10519252
- Publisher / Repository:
- Nature Astronomy
- Date Published:
- Journal Name:
- Nature Astronomy
- Edition / Version:
- 1
- Volume:
- 8
- Issue:
- 3
- ISSN:
- 2397-3366
- Page Range / eLocation ID:
- 328 to 336
- 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/10.1038/s41550-023-02161-z
