scholarly journals Maximum Mass of Hybrid Stars in the Quark Bag Model

Astrophysics ◽  
2017 ◽  
Vol 60 (4) ◽  
pp. 563-571 ◽  
Author(s):  
G. B. Alaverdyan ◽  
Yu. L. Vartanyan
Keyword(s):  
Maximum Mass ◽  
Bag Model ◽  
Hybrid Stars

scholarly journals SU(2) Chiral Sigma Model Study of Phase Transition in Hybrid Stars

2003 ◽  
Vol 18 (30) ◽  
pp. 2135-2145 ◽  
Author(s):  
P. K. Jena ◽  
L. P. Singh
Keyword(s):  
Phase Transition ◽  
Neutron Star ◽  
Nuclear Matter ◽  
Quark Matter ◽  
Sigma Model ◽  
Maximum Mass ◽  
Model Study ◽  
Stable Solutions ◽  
Hybrid Stars ◽  
Matter Component

We use a modified SU(2) chiral sigma model to study nuclear matter component and simple bag model for quark matter constituting a neutron star. We also study the phase transition of nuclear matter to quark matter with the mixed phase characterized by two conserved charges in the interior of highly dense neutron stars. Stable solutions of Tolman–Oppenheimer–Volkoff equations representing hybrid stars are obtained with a maximum mass of 1.67M⊙ and radius around 8.9 km.

scholarly journals Contraction of cold neutron star due to in the presence a quark core

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
B. Eslam Panah ◽  
T. Yazdizadeh ◽  
G. H. Bordbar
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Quark Matter ◽  
Average Density ◽  
Dynamical Stability ◽  
Hadronic Matter ◽  
Maximum Mass ◽  
Quark Core ◽  
Hybrid Stars ◽  
Schwarzschild Radius

Abstract Motivated by importance of the existence of quark matter on structure of neutron star. For this purpose, we use a suitable equation of state (EoS) which include three different parts: (i) a layer of hadronic matter, (ii) a mixed phase of quarks and hadrons, and, (iii) a strange quark matter in the core. For this system, in order to do more investigation of the EoS, we evaluate energy, Le Chatelier’s principle and stability conditions. Our results show that the EoS satisfies these conditions. Considering this EoS, we study the effect of quark matter on the structure of neutron stars such as maximum mass and the corresponding radius, average density, compactness, Kretschmann scalar, Schwarzschild radius, gravitational redshift and dynamical stability. Also, considering the mentioned EoS in this paper, we find that the maximum mass of hybrid stars is a little smaller than that of the corresponding pure neutron star. Indeed the maximum mass of hybrid stars can be quite close to the pure neutron stars. Our calculations about the dynamical stability show that these stars are stable against the radial adiabatic infinitesimal perturbations. In addition, our analyze indicates that neutron stars are under a contraction due to the existence of quark core.

RADIAL PULSATIONS OF HYBRID NEUTRON STARS

2012 ◽  
Vol 18 ◽  
pp. 105-108 ◽  
Author(s):  
C. VÁSQUEZ FLORES ◽  
C. H. LENZI ◽  
G. LUGONES
Keyword(s):  
Stability Criterion ◽  
Mean Field ◽  
Oscillation Mode ◽  
Maximum Mass ◽  
Mean Field Model ◽  
Relativistic Mean Field ◽  
Hadron Phase ◽  
Njl Model ◽  
Hybrid Stars ◽  
The Stability

In this work we investigate the adiabatic radial oscillations of hybrid stars. We use a relativistic-mean-field model equation of state (EOS) to describe the hadron phase and the Nambu-Jona-Lasinio (NJL) model for the quark matter phase. We integrate the equations of relativistic radial oscillations using different parameterizations for the NJL model and investigate the effect of a first order hadron-quark phase transition on the fundamental oscillation mode. The results show that the period τ of the fundamental mode is characterized by a cusp on the maximum mass and is finite for some configurations beyond the maximum mass. We conclude that for hybrid stars with sharp discontinuities the standard stability criterion ∂M/∂εc > 0 is not coincident with the stability criterion based on the finiteness of τ.

scholarly journals Strange Stars in the Vector Interaction Enhanced Bag Model

Particles ◽  
2019 ◽  
Vol 2 (4) ◽  
pp. 447-456 ◽  
Author(s):  
Marc Salinas ◽  
Thomas Klähn ◽  
Prashanth Jaikumar
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Parameter Space ◽  
Chiral Symmetry Breaking ◽  
Maximum Mass ◽  
Bag Model ◽  
Strange Stars ◽  
Strange Matter ◽  
Vector Interaction ◽  
The Stability

The vector interaction enhanced Bag model (vBag) for dense quark matter extends the commonly used thermodynamic Bag model (tdBag) by incorporating effects of dynamical chiral symmetry breaking (D χ SB) and vector repulsion. Motivated by the suggestion that the stability of strange matter is in tension with chiral symmetry breaking (D χ SB) we examine the parameter space for its stability in the vBag model in this work. Assuming the chiral transition occurs at sufficiently low density, we determine the stability region of strange matter as a function of the effective Bag constant and the vector coupling. As an astrophysical application, we construct contours of maximum mass M max and radius at maximum mass R max in this region of parameter space. We also study the stability of strange stars in the vBag model with maximum mass in the 2 M ⊙ range by computing the spectrum of radial oscillations, and comparing to results from the tdBag model, find some notable differences.

scholarly journals PHASE TRANSITION AND HYBRID STAR IN AN SU(2) CHIRAL SIGMA MODEL

2002 ◽  
Vol 17 (40) ◽  
pp. 2633-2646 ◽  
Author(s):  
P. K. JENA ◽  
L. P. SINGH
Keyword(s):  
Phase Transition ◽  
Nuclear Matter ◽  
Quark Matter ◽  
Sigma Model ◽  
Mean Field ◽  
Maximum Mass ◽  
Hybrid Star ◽  
Field Approach ◽  
Stable Solutions ◽  
Hybrid Stars

We use a modified SU(2) chiral sigma model to study nuclear matter at high density using mean field approach. We also study the phase transition of nuclear matter to quark matter in the interior of highly dense neutron stars. Stable solutions of Tolman–Oppenheimer–Volkoff equations representing hybrid stars are obtained with a maximum mass of 1.69M⊙, radii around 9.3 km and a quark matter core constituting nearly 55–85% of the star radii.

scholarly journals Locating the special point of hybrid neutron stars

2022 ◽  
Vol 258 ◽  
pp. 07009
Author(s):  
Mateusz Cierniak ◽  
David Blaschke
Keyword(s):  
Neutron Stars ◽  
Sound Speed ◽  
Transition Density ◽  
Mass Range ◽  
Special Point ◽  
Model Parameters ◽  
Maximum Mass ◽  
Upper Limit ◽  
Pressure Scale ◽  
Hybrid Stars

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 (cs2) 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 < Cs min2 < 0.43 and 80 < A[MeV/fm3] < 160. The upper limit for the maximum mass of hybrid stars depends on the upper limit for cs2 so that choosing cs,max2 = 0.6 results in Mmax < 2.7 M⊙, within the mass range of GW190814.

Strange quark mass effect on the structure of hybrid stars

2018 ◽  
Vol 27 (01) ◽  
pp. 1850006 ◽  
Author(s):  
Jian-Feng Xu ◽  
Yan-An Luo ◽  
Lei Li ◽  
Guang-Xiong Peng
Keyword(s):  
Quark Matter ◽  
Quark Mass ◽  
Strange Quark ◽  
Mass Effect ◽  
Compact Stars ◽  
Model Parameters ◽  
Maximum Mass ◽  
Strange Quark Mass ◽  
Wide Range ◽  
Hybrid Stars

We study the strange quark mass effect on the phase diagram of strong interaction and the structure of compact stars with a thermodynamically enhanced perturbative QCD model by matching quark matter onto nuclear matter using the Gibbs conditions. It is found that the mass effect of strange quark matter can obviously stiffen the equation of state of mixed phases and result in more massive hybrid stars (HSs), while that usually lowers the maximum mass of pure quark stars. Given reasonable model parameters, the maximum mass of HSs can reach two times the solar mass and the stars always have mixed-phase core in a considerably wide range of model parameters.

Sign in / Sign up

Export Citation Format

Share Document