Treating quarks within neutron stars

2019/06/30 by Sophia Han, M. A. A. Mamun, S. Lalit +5 · 2 citations
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics #Condensed matter physics #Equation of state #Gamma-ray bursts and supernovae #Hadron #High-pressure geophysics and materials #Neutron star #Nuclear matter #Nuclear physics #Nucleon #Particle physics #Phase transition #Physics #Pulsars and Gravitational Waves Research #Quantum chromodynamics #Quantum mechanics #Quark #Stars #Strange matter #astro-ph.HE #astro-ph.SR #nucl-th

paper · pdf · doi:10.1103/physrevd.100.103022

published as Phys. Rev. D 100, 103022 (2019) · 24 pages, 8 figures, 7 tables; accepted for publication in PRD

arxiv created 2019/10/31 · openalex publication_date 2019/11/25 · arxiv updated 2020/06/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06

Abstract

Neutron star interiors provide the opportunity to probe properties of cold dense matter in the QCD phase diagram. Utilizing models of dense matter in accord with nuclear systematics at nuclear densities, we investigate the compatibility of deconfined quark cores with current observational constraints on the maximum mass and tidal deformability of neutron stars. We explore various methods of implementing the hadron-to-quark phase transition, specifically, first-order transitions with sharp (Maxwell construction) and soft (Gibbs construction) interfaces, and smooth crossover transitions. We find that within the models we apply, hadronic matter has to be stiff for a first-order phase transition and soft for a crossover transition. In both scenarios and for the equations of state we employed, quarks appear at the center of premerger neutron stars in the mass range \ensuremath≈1.0--1.6 M_\ensuremath\bigodot, with a squared speed of sound c_QM²\ensuremath\gtrsim0.4 characteristic of strong repulsive interactions required to support the recently discovered neutron star masses \ensuremath≥2 M_\ensuremath\bigodot. We also identify equations of state and phase transition scenarios that are consistent with the bounds placed on tidal deformations of neutron stars in the recent binary merger event GW170817. We emphasize that distinguishing hybrid stars with quark cores from normal hadronic stars is very difficult from the knowledge of masses and radii alone, unless drastic sharp transitions induce distinctive disconnected hybrid branches in the mass-radius relation.

Citations

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Cited by

• Neutron stars with large quark cores
• Constraining the onset density of the hadron-quark phase transition with gravitational-wave observations