An Equation of State with the Complete SU(3)f Baryon Octet for Neutron Star Mergers

Above 2–3 times saturation density (n0), the neutron star equation of state (EoS) is predicted to contain strange quarks, but it is difficult to model the strange degrees of freedom in a way that correctly predicts a maximum neutron star mass in excess of the heaviest known neutron stars, such as PSR J0740+6620 (2.08 ± 0.07 M⊙), and which correctly predicts the radius and tidal deformability of neutron stars, particularly that measured for the predecessors of GW170817. We also demonstrate that existing density-dependent relativistic-mean-field (DD-RMF) EoSs do not accurately predict the single-particle potential of hyperons in both symmetric and neutron matter at n0, as predicted by the HALQCD Collaboration’s lattice QCD-informed Br¨uckner–Hartree–Fock (BHF) model. We develop a new EoS, DID (for “density- and isospin-dependent”), that includes the complete SU(3)f ground-state baryon octet as well as a novel isospin-density dependence. It correctly predicts the HALQCD hyperon potentials and is consistent with neutron star observables, including the maximum mass. The cold β-equilibrated EoS features a Σ− baryon that appears before the Λ, as well as a c 2 s that peaks near 0.71 around 4 n0 and dips to around 0.54 near 6.5 n0. A software tool has also been constructed for solving DD-RMF EoSs and the Hempel–SchaffnerBielich crust model.

Name thesis:degree_name

Doctor of Philosophy

Discipline thesis:degree_discipline

Physics

Grantor

University of Houston

Year dc:date.issued

2025

Author dc:creator

• Frohaug, Gabriel Brahm 2002-

Advisor dc:contributor.advisor

• Ratti, Claudia

Committee members dc:contributor.committeemember

• Ordonez, Carlos
• Quaini, Annalisa
• Bellwied, Rene

• Neutron star
• Hyperon
• Relativistic mean field

Language dc:language.iso

English

Handle dc:identifier.uri

https://hdl.handle.net/10657/20921

OAI identifier oai:identifier

oai:uh-ir.tdl.org:10657/20921