Locating the special point of hybrid neutron stars

Abstract

The special point is a feature unique to models of hybrid neutron stars. It represents a location on their mass--radius sequences that is insensitive to the phase transition density. We consider hybrid neutron stars with a core of deconfined quark matter that obeys a constant--sound--speed (CSS) equation of state model and provide a fit formula for the coordinates of the special point as functions of the squared sound speed ($c_s^2$) and pressure scale ($A$) parameters. Using the special point mass as a proxy for the maximum mass of the hybrid stars we derive limits for the CSS model parameters based on the recent NICER constraint on mass and radius of pulsar PSR J0740+6620, $0.36<{c_s^2}_{\min }<0.43$ and $80<A[{MeV/fm}^3]<160$. The upper limit for the maximum mass of hybrid stars depends on the upper limit for $c_s^2$ so that choosing $c_{s,max}^2=0.6$ results in $M_{\max }<2.7M_{\odot }$, within the mass range of GW190814.

arXiv comment8 pages, 5 figures, 1 table

References in corpus (28)

• Shapiro delay measurement of a two solar mass neutron star
• The equation of state for nucleon matter and neutron star structure
• Tidal deformability of neutron stars with realistic equations of state and their gravitational wave signatures in binary inspiral
• Gravitational-wave constraints on the neutron-star-matter Equation of State
• Composition and thermodynamics of nuclear matter with light clusters
• From hadrons to quarks in neutron stars: a review
• Neutron-star radius constraints from GW170817 and future detections
• Generic conditions for stable hybrid stars
• Identifying a first-order phase transition in neutron star mergers through gravitational waves
• Stringent constraints on neutron-star radii from multimessenger observations and nuclear theory
• Do hyperons exist in the interior of neutron stars ?
• Maximum mass of neutron stars and strange neutron-star cores
• The phase diagram of three-flavor quark matter under compact star constraints
• Implications of the measurement of pulsars with two solar masses for quark matter in compact stars and HIC. A NJL model case study
• Hadron-Quark Crossover and Massive Hybrid Stars
• Equation of state constraints from the threshold binary mass for prompt collapse of neutron star mergers
• Constraints on Neutron Star Properties from X-ray Observations of Millisecond Pulsars
• Quark-Nuclear Hybrid EoS with Excluded Volume Effects
• Phases of dense matter in compact stars
• Was GW170817 a canonical neutron star merger? Bayesian analysis with a third family of compact stars
• Hyperon-mixed neutron star with universal many-body repulsion
• Classifications of Twin Star Solutions for a Constant Speed of Sound Parameterized Equation of State
• Studying the onset of deconfinement with multi-messenger astronomy of neutron stars
• Neutron-star radii based on realistic nuclear interactions
• The special point on the hybrid star mass--radius diagram and its multi--messenger implications
• Hybrid neutron stars in the mass-radius diagram
• Special point on the mass radius diagram of hybrid stars
• How strange are compact star interiors ?

Cited by in corpus (7)

• Quark-nuclear hybrid equation of state for neutron stars under modern observational constraints
• Recovering the conformal limit of color superconducting quark matter within a confining density functional approach
• Hybrid star phenomenology from the properties of the special point
• Implications of supermassive neutron stars for the form of the equation of state of hybrid stars
• Special point "trains" in the M-R diagram of hybrid stars
• Compact Star Twins with a Dark Matter Core
• Density functional approach to quark matter with confinement and color superconductivity