The special point on the hybrid star mass--radius diagram and its multi--messenger implications

Abstract

We show the existence and investigate the location of the special point (SP) in which hybrid neutron star mass-radius (M-R) curves have to cross each other when they belong to a class of hybrid equation of state (EoS) constructed with generic constant--speed--of--sound (CSS) quark matter models for which the onset deconfinement is varied. We demonstrate that for a three-parameter CSS model the position of the SP in the M-R diagram is largely independent of the choice of the hadronic EoS, but in dependence on the stiffness of the quark matter EoS it spans a region that we identify. We find that the difference between the maximum mass and the SP mass depends on the mass at the onset of deconfinement so that an upper limit of $0.19M_{\odot }$ for this difference is obtained from which a lower limit on the radius of hybrid stars is deduced. Together with a lower limit on the radius of hadronic stars, derived from a class of reasonably soft hadronic EoS including hyperons, we identify a region in the M-R diagram which can be occupied only by hybrid stars. Accordingly, we suggest that a NICER radius measurement on the massive pulsar PSR J0740+6620 in the range of 8.6-11.9 km would indicate that this pulsar is a hybrid neutron star with deconfined quark matter in the inner core.

9 pages, 4 figures; figures 2 and 4 have been modified and discussion of hypernuclear matter is added

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Cited by in corpus (24)

• Studying the onset of deconfinement with multi-messenger astronomy of neutron stars
• The Radius of PSR J0740+6620 from NICER and XMM-Newton Data
• Recovering the conformal limit of color superconducting quark matter within a confining density functional approach
• Hybrid neutron stars in the mass-radius diagram
• Speed of Sound in Hybrid Stars and the Role of Bag Pressure in the Emergence of Special Points on M-R Variation of Hybrid Stars
• Constraints on Density Dependent MIT Bag Model Parameters for Quark and Hybrid Stars
• Neutron star properties with careful parameterization in the (axial)vector meson extended linear sigma model
• Hybrid star phenomenology from the properties of the special point
• A Detailed Analysis of the Special Points on $M-R$ Solutions of Hybrid (Twin) Stars
• Studying VLOCV twin compact stars with binary mergers
• Hybrid stars with reactive interfaces: analysis within the Nambu-Jona-Lasinio model
• Bayesian analysis of hybrid neutron star EOS constraints within an instantaneous nonlocal chiral quark matter model
• Spherically symmetric anisotropic strange stars
• Locating the special point of hybrid neutron stars
• Impact of Multiple Phase Transitions in Dense QCD on Compact Stars
• Direct nonparametric multimessenger constraints on the equation of state of cold dense nuclear matter
• Investigating the Impact of Higher-Order Phase Transitions in Binary Neutron-Star Mergers
• Fastest spinning millisecond pulsars: indicators for quark matter in neutron stars?
• Special point "trains" in the M-R diagram of hybrid stars
• Rapidly Spinning Massive Pulsars as an Indicator of Quark Deconfinement
• Early deconfinement of asymptotically conformal color-superconducting quark matter in neutron stars
• Recurring region for neutron-star observables
• Tidal Deformability of Quark Stars with Repulsive Interactions
• Density functional approach to quark matter with confinement and color superconductivity