Relativistic hybrid stars in light of the NICER PSR J0740 + 6620 radius measurement

Journal Article · 21 December 2021 · Physical Review. D.

DOI: https://doi.org/10.1103/physrevd.104.l121302 · OSTI ID:1837694

Li, Jia Jie  ^[1]; Sedrakian, Armen  ^[2]; Alford, Mark  ^[3]

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1. Southwest Univ., Chongqing (China); Washington University in St. Louis
2. Univ. of Wroclaw (Poland)
3. Washington Univ., St. Louis, MO (United States)

We explore the implications of the recent radius determination of PSR J0740 + 6620 by the NICER experiment, combined with the neutron skin measurement by the PREX-II experiment and the associated inference of the slope of symmetry energy, for the structure of hybrid stars with a strong first-order phase transition from nucleonic to quark matter. Furthermore, we combine a covariant density-functional nucleonic equation of state (EOS) with a constant-speed-of-sound EOS for quark matter. We show that the radius and tidal deformability ranges obtained from GW170817 can be reconciled with the implication of the PREX-II experiment if there is a phase transition to quark matter in the low-mass compact star. In the high-mass segment, the EOS needs to be stiff to comply with the large-radius inference for PSR J0740 + 6620 and J0030 + 0451 with masses M ≃ 2 M_⊙ and M≃1.4 M⊙. We show that twin stars are not excluded, but the mass and radius ranges (with M ≥ M_⊙) are restricted to narrow domains ΔM_twin ≲ 0.05 M_⊙ and ΔR_twin ~ 1.0 km. We also show that the existence of twin configurations is compatible with the light companion in the GW190814 event being a hybrid star in the case of values of the sound-speed square s = 0.6 and s = 1/3.

• Research Organization: Washington Univ., St. Louis, MO (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• Grant/Contract Number: FG02-05ER41375
• OSTI ID: 1837694
• Journal Information: Physical Review. D., Journal Name: Physical Review. D. Journal Issue: 12 Vol. 104; ISSN 2470-0010
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English