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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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Hyperonization in Compact Stars
We review the covariant density functional approach to the equation of state of the dense nuclear matter in compact stars. The main emphasis is on the hyperonization of the dense matter, and the role played by the Delta-resonance. The implications of hyperonization for the astrophysics of compact stars, including the equation of state, composition, and stellar parameters are examined. The mass-radius relation and tidal deformabilities of static and rapidly rotating (Keplerian) configurations are discussed in detail. We briefly touch upon some other recent developments involving hyperonization in hot hypernuclear matter at high- and low-densities.
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- PAR ID:
- 10280163
- Editor(s):
- Vasconcellos, C; and Weber, F.
- Date Published:
- Journal Name:
- World Scientific series in astrophysics
- ISSN:
- 2529-7511
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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