The sharpness of the quark-hadron transition and the properties of hybrid stars

Abstract

We investigate the effects of the sharpness of the phase transition between hadronic matter and quark matter on various properties of neutron stars. We construct hybrid equations of state by combining a hadronic model with a quark model using a Gaussian function. This approach introduces a smooth transition characterized by two parameters: one representing the overpressure relative to the first-order phase transition point, and the other related to the range over which the hybrid region extends in baryon chemical potential. We find that the sharpness of the phase transition significantly influences the equation of state, which can deviate by several tens of ${\text{MeV fm}}^{-3}$ from the one with a sharp first-order transition. The speed of sound exhibits diverse behaviors, including drastic drops, pronounced peaks, and oscillatory patterns, depending on the sharpness parameters. In terms of stellar structure, while the maximum neutron star mass remains largely unaffected by the sharpness of the phase transition, the stellar radii can vary significantly. Smoother transitions lead to a leftward shift (up to 1 km) of the mass-radius curve segment corresponding to hybrid stars. The tidal deformability decreases with smoother transitions, especially for higher-mass stars. Our results are quite general and do not qualitatively depend on the specific hadronic and quark matter models employed. In fact, the hybrid equation of state and stellar properties derived from microscopic models of quark-hadron pasta phases display the same behavior as described above.

References in corpus (18)

• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• PSR J0030+0451 Mass and Radius from NICER Data and Implications for the Properties of Neutron Star Matter
• A NICER View of PSR J0030+0451: Millisecond Pulsar Parameter Estimation
• A NICER View of the Massive Pulsar PSR J0740+6620 Informed by Radio Timing and XMM-Newton Spectroscopy
• Neutron matter at next-to-next-to-next-to-leading order in chiral effective field theory
• Cold quark matter at N3LO: soft contributions
• A Parametrized Equation of State for Neutron Star Matter with Continuous Sound Speed
• The QCD phase diagram and Beam Energy Scan physics: a theory overview
• Modified MIT bag Models -- part I: Thermodynamic consistency, stability windows and symmetry group
• Nonperturbative quark matter equations of state with vector interactions
• Modified MIT Bag Models -- part II: QCD phase diagram and hot quark stars
• Remarks on nuclear matter: how an ${\omega }_0$ condensate can spike the speed of sound, and a model of $Z(3)$ baryons
• Surface tension of highly magnetized degenerate quark matter
• Higher-Order Cumulants and Correlation Functions of Proton Multiplicity Distributions in $\sqrt{s_{\mathrm{NN}}}$ = 3 GeV Au+Au Collisions at the RHIC STAR Experiment
• Hybrid neutron stars in the mass-radius diagram
• Quark-hadron pasta phase in neutron stars: the role of medium-dependent surface and curvature tensions
• Hybrid stars can be self-bound