Stable anisotropic dissipative quark star with tilted observer

2018 ◽  
Vol 33 (18) ◽  
pp. 1850102 ◽  
Author(s):  
M. Sharif ◽  
Sobia Sadiq
Keyword(s):  
Physical Properties ◽  
Compact Object ◽  
Fluid Distribution ◽  
Spherically Symmetric ◽  
Quark Star ◽  
Field Equations ◽  
Dynamical Equations ◽  
Free Condition ◽  
Quark Stars ◽  
Mit Bag Model

This paper is aimed to study spherically symmetric anisotropic dissipative quark star for tilted observer. The corresponding field equations as well as dynamical equations are formulated. We consider the MIT bag model for quark stars and investigate numerical solution of the field equations by imposing the shear-free condition. It is found that all the expected physical properties are present related to stellar fluid distribution. Finally, we analyze stability of the compact object by analyzing splitting of the fluid distribution. It is found that radial velocity does not change its sign during evolution of the system implying that the system does not undergo splitting and remains stable.

Study of tilted cylindrical quark star

2020 ◽  
Vol 35 (14) ◽  
pp. 2050110
Author(s):  
M. Sharif ◽  
Sumaira Nazir
Keyword(s):  
Numerical Solution ◽  
Energy Conditions ◽  
Fluid Distribution ◽  
Quark Star ◽  
Field Equations ◽  
Dynamical Equations ◽  
Stellar Matter ◽  
Mit Bag Model ◽  
Pressure Anisotropy ◽  
Physical Features

In this paper, we study perfect, anisotropic and anisotropic dissipative cylindrical quark star for the tilted observer. To this end, the field equations and dynamical equations are formulated and assume MIT bag model to find a numerical solution of the field equations. The behavior of resulting model is investigated by plotting density, pressure, anisotropy and energy conditions. We check viability of the solutions through physical features related to stellar matter configuration. Finally, we discuss stability for all the cases of fluid distribution.

scholarly journals Decoupled Embedding Class-One Strange Stars in Self-Interacting Brans–Dicke Gravity

Universe ◽  
2021 ◽  
Vol 7 (6) ◽  
pp. 161
Author(s):  
Muhammad Sharif ◽  
Amal Majid
Keyword(s):  
Fluid Distribution ◽  
Quark Star ◽  
Field Equations ◽  
Additional Source ◽  
Massive Scalar Field ◽  
Star Models ◽  
Embedding Class One ◽  
Mit Bag Model ◽  
Embedding Condition ◽  
Anisotropic Source

This work aims to extend two isotropic solutions to the anisotropic domain by decoupling the field equations in self-interacting Brans–Dicke theory. The extended solutions are obtained by incorporating an additional source in the isotropic fluid distribution. We deform the radial metric potential to disintegrate the system of field equations into two sets such that each set corresponds to only one source (either isotropic or additional). The system related to the anisotropic source is solved by employing the MIT bag model as an equation of state. Further, we develop two isotropic solutions by plugging well-behaved radial metric potentials in Karmarkar’s embedding condition. The junction conditions at the surface of the star are imposed to specify the unknown constants appearing in the solution. We examine different physical characteristics of the constructed quark star models by using the mass and radius of PSR J1903+327. It is concluded that, in the presence of a massive scalar field, both stellar structures are well-behaved, viable and stable for smaller values of the decoupling parameter.

Impact of f(R,T) gravity in evolution of charged viscous fluids

2021 ◽  
Vol 30 (04) ◽  
pp. 2150027
Author(s):  
I. Noureen ◽  
Usman-ul-Haq ◽  
S. A. Mardan
Keyword(s):  
Stability Analysis ◽  
Energy Momentum Tensor ◽  
Momentum Tensor ◽  
Viscous Fluids ◽  
Fluid Distribution ◽  
Perturbation Scheme ◽  
Field Equations ◽  
Dynamical Equations ◽  
Stability Of Stars ◽  
The Stability

In this work, the evolution of spherically symmetric charged anisotropic viscous fluids is discussed in framework of [Formula: see text] gravity. In order to conduct the analysis, modified Einstein Maxwell field equations are constructed. Nonzero divergence of modified energy momentum tensor is taken that implicates dynamical equations. The perturbation scheme is applied to dynamical equations for stability analysis. The stability analysis is carried out in Newtonian and post-Newtonian limits. It is observed that charge, fluid distribution, electromagnetic field, viscosity and mass of the celestial objects greatly affect the collapsing process as well as stability of stars.

Study of some compact objects in R + 2βT gravity

2019 ◽  
Vol 28 (16) ◽  
pp. 2040005
Author(s):  
Arfa Waseem ◽  
M. Sharif
Keyword(s):  
Stellar System ◽  
Graphical Analysis ◽  
Compact Objects ◽  
Stellar Structure ◽  
Energy Conditions ◽  
Spherically Symmetric ◽  
Field Equations ◽  
Star Models ◽  
Mit Bag Model ◽  
Text Model

The aim of this work is to examine the nature as well as physical characteristics of anisotropic spherically symmetric stellar candidates in the context of [Formula: see text] gravity. We assume that the fluid components such as pressure and energy density are related through MIT bag model equation-of-state in the interior of stellar system. In order to analyze the structure formation of some specific star models, the field equations are constructed using Krori–Barua solution in which the unknown constants are evaluated by employing observed values of radii and masses of the considered stars. We check the consistency of [Formula: see text] model through the graphical analysis of energy conditions as well as stability of stellar structure. It is found that our considered stars show viable as well as stable behavior for this model.

Exact solutions of the Einstein–Maxwell equations with linear equation of state

2012 ◽  
Vol 90 (12) ◽  
pp. 1179-1183 ◽  
Author(s):  
Tooba Feroze
Keyword(s):  
Equation Of State ◽  
Linear Equation ◽  
Maxwell Equations ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Fluid Distribution ◽  
Spherically Symmetric ◽  
Field Equations ◽  
General Linear Equation ◽  
Energy Momentum Conservation

Two new classes of solutions of the Einstein–Maxwell field equations are obtained by substituting a general linear equation of state into the energy–momentum conservation equation. We have considered static, anisotropic, and spherically symmetric charged perfect fluid distribution of matter with a particular form of gravitational potential. Expressions for the mass–radius ratio, the surface, and the central red shift horizons are given for these solutions.

GRAVITATIONAL COLLAPSE OF SPHERICALLY SYMMETRIC ANISOTROPIC FLUID WITH HOMOTHETIC SELF-SIMILARITY

2003 ◽  
Vol 12 (07) ◽  
pp. 1315-1332 ◽  
Author(s):  
C. F. C. BRANDT ◽  
M. F. A. DA SILVA ◽  
JAIME F. VILLAS DA ROCHA ◽  
R. CHAN
Keyword(s):  
Physical Properties ◽  
Gravitational Collapse ◽  
Energy Conditions ◽  
Anisotropic Fluid ◽  
Spherically Symmetric ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Self Similarity ◽  
Tangential Pressure

We study spacetimes of spherically symmetric anisotropic fluid with homothetic self-similarity. We find a class of solutions to the Einstein field equations by assuming that the tangential pressure of the fluid is proportional to its radial one and that the fluid moves along time-like geodesics. The energy conditions, and geometrical and physical properties of these solutions are studied and found that some of them represent gravitational collapse of an anisotropic fluid.

scholarly journals Static spherically symmetric three-form stars

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Bruno J. Barros ◽  
Zahra Haghani ◽  
Tiberiu Harko ◽  
Francisco S. N. Lobo
Keyword(s):  
Equations Of State ◽  
Field Potential ◽  
Compact Object ◽  
Momentum Tensor ◽  
Einstein Condensate ◽  
Gravity Theory ◽  
Spherically Symmetric ◽  
Field Equations ◽  
Potential Term ◽  
Form Field

AbstractWe consider interior static and spherically symmetric solutions in a gravity theory that extends the standard Hilbert–Einstein action with a Lagrangian constructed from a three-form field $$A_{\alpha \beta \gamma }$$ A α β γ , which generates, via the field strength and a potential term, a new component in the total energy-momentum tensor of the gravitational system. We formulate the field equations in Schwarzschild coordinates and investigate their solutions numerically for different equations of state of neutron and quark matter, by assuming that the three-field potential is either a constant or possesses a Higgs-like form. Moreover, stellar models, described by the stiff-fluid, radiation-like, bag model and the Bose–Einstein condensate equations of state are explicitly obtained in both general relativity and three-form gravity, thus allowing an in-depth comparison between the astrophysical predictions of these two gravitational theories. As a general result we find that, for all the considered equations of state, three-form field stars are more massive than their general relativistic counterparts. As a possible astrophysical application, we suggest that the 2.5$$ M_{\odot }$$ M ⊙ mass compact object, associated with the GW190814 gravitational wave event, could be in fact a neutron or a quark star described by the three-form gravity theory.

scholarly journals Physical Attributes of Bardeen Stellar Structures in f R Gravity

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
M. Farasat Shamir ◽  
Ammara Usman ◽  
Tayyaba Naz
Keyword(s):  
Black Hole ◽  
Compact Object ◽  
Specific Form ◽  
Surface Boundary ◽  
Spherically Symmetric ◽  
Field Equations ◽  
Anisotropic Matter ◽  
Physical Attributes ◽  
Hole Model ◽  
Symmetric Spacetime

The main aim of our study is to explore some relativistic configurations of compact object solution in the background of f R gravity, by adopting the Krori-Barua spacetime. In this regard, we establish the field equations for spherically symmetric spacetime along with charged anisotropic matter source by assuming the specific form of the metric potentials, i.e., ν r = B r 2 + C and λ r = A r 2 . Further, to calculate the constant values, we consider the Bardeen model as an exterior spacetime at the surface boundary. To ensure the viability of the f R gravity model, the physical characteristics including energy density, pressure components, energy bonds, equilibrium condition, Herrera cracking concept, mass-radius relation, and adiabatic index are analyzed in detail. It is observed that all the outcomes by graphical exploration and tabular figures show that the Bardeen black hole model describes the physically realistic stellar structures.

scholarly journals Quark Stars in Massive Brans–Dicke Gravity with Tolman–Kuchowicz Spacetime

Universe ◽  
2020 ◽  
Vol 6 (8) ◽  
pp. 124
Author(s):  
Amal Majid ◽  
M. Sharif
Keyword(s):  
Scalar Field ◽  
Coupling Parameter ◽  
Realistic Model ◽  
Stellar Model ◽  
Junction Conditions ◽  
Anisotropic Model ◽  
Field Equations ◽  
Quark Stars ◽  
Mit Bag Model ◽  
Bag Constant

In this paper, we construct anisotropic model representing salient features of strange stars in the framework of massive Brans–Dicke gravity. We formulate the field equations for Tolman–Kuchowicz ansatz by incorporating the MIT bag model. Junction conditions are applied on the boundary of the stellar model to evaluate the unknown constants in terms of mass and radius of the star. The radius of the strange star candidate PSR J1614-2230 is predicted by assuming maximum anisotropy at the surface of the star for different values of the coupling parameter, mass of the scalar field and bag constant. We examine various properties as well as the viability and stability of the anisotropic sphere. We conclude that the astrophysical model agrees with the essential criteria of a physically realistic model for higher values of the coupling parameter as well as mass of the scalar field.

scholarly journals Reduction of the Mass of the Proto-Quark Star during Cooling

Particles ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 37-44
Author(s):  
Gevorg Hajyan
Keyword(s):  
Quark Matter ◽  
Finite Temperature ◽  
Supernova Explosion ◽  
Neutrino Emission ◽  
Quark Star ◽  
Bag Model ◽  
Quark Stars ◽  
Mit Bag Model

The integral parameters (mass, radius) of hot proto-quark stars that are formed in supernova explosion are studied. We use the MIT bag model to determine the pressure of up-down and strage quark matter at finite temperature and in the regime where neutrinos are trapped. It is shown that such stars are heated to temperatures of the order of tens of MeV. The maximum possible values of the central temperatures of these stars are determined. It is shown that the energy of neutrinos that are emitted from proto-quark stars is of the order of 250÷300 MeV. Once formed, the proto-quark stars cool by neutrino emission, which leads to a decrease in the mass of these stars by about 0.16–0.25 M⊙ for stars with the rest masses that are in the range Mb=1.22−1.62M⊙.

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