Maximal mass of the neutron star with a deconfined quark core

Abstract

The nature of equation of state for the matter in the neutron star plays an important role in determining its maximal mass. In addition, it must comply with the condition of causality. Noting that the central density of a maximally massive neutron star is well above the nuclear saturation density, a deconfined quark core in the central region is motivated in this paper. We analyze this scenario by employing the MIT bag model to represent the core region and one of the unified equations of state for the region outside the core. Such combination is found to solve the problem of causality violation. In each case of the combined equations of state, the radial profile of $\rho r^2$ displays a peak and dominant contribution to the total mass of the star comes from the region around the peak value of $\rho r^2$, whereas the contribution is small from the regions near the center and the surface. This peak occurs in the region of hadronic matter for the combinations considered in this paper. Importantly, we find that the position of the peak in $\rho r^2$ is well-correlated with the maximal mass -- the highest value of $1.98M_{\odot }$ obtains for the case with the peak occurring farthest from the center. This gravitational threshold being obtained for a non-rotating neutron star, we expect the threshold to lie well above 2 $M_{\odot }$ for a rapidly rotating neutron star, that may explain the existance of massive pulsars from recent astronomical observations.

References in corpus (25)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• The equation of state for nucleon matter and neutron star structure
• GW190814: Gravitational Waves from the Coalescence of a 23 M${}_{\odot }$ Black Hole with a 2.6 M${}_{\odot }$ Compact Object
• GW190425: Observation of a Compact Binary Coalescence with Total Mass $\sim 3.4M_{\odot }$
• Relativistic Shapiro delay measurements of an extremely massive millisecond pulsar
• Masses, Radii, and Equation of State of Neutron Stars
• Constraints on a phenomenologically parameterized neutron-star equation of state
• From hadrons to quarks in neutron stars: a review
• The NANOGrav Nine-year Data Set: Mass and Geometric Measurements of Binary Millisecond Pulsars
• Further explorations of Skyrme-Hartree-Fock-Bogoliubov mass formulas. XII: Stiffness and stability of neutron-star matter
• PSR J0952-0607: The Fastest and Heaviest Known Galactic Neutron Star
• Relativistic Mean-Field Theory and the High-Density Nuclear Equation of State
• Hyperon Puzzle: Hints from Quantum Monte Carlo Calculations
• Peering into the dark side: magnesium lines establish a massive neutron star in PSR J2215+5135
• Rotating Stars in Relativity
• Inner crust of neutron stars with mass-fitted Skyrme functionals
• Chiral Effective Field Theory and the High-Density Nuclear Equation of State
• On the appearance of hyperons in neutron stars
• Relativistic parameterizations of neutron matter and implications for neutron stars
• LOFAR discovery of the fastest-spinning millisecond pulsar in the Galactic field
• Relativistic models of the neutron-star matter equation of state
• Phenomenological neutron star equations of state: 3-window modeling of QCD matter
• Neutron Star Matter as a Relativistic Fermi Liquid

Cited by in corpus (1)

• Recent progresses in strange quark stars