Model of a static spherically symmetric anisotropic fluid distribution in paraboloidal spacetime admitting a polytropic equation of state

2020 ◽  
Vol 135 (8) ◽  
Author(s):  
S. Thirukkanesh ◽  
Ranjan Sharma ◽  
Shyam Das
Keyword(s):  
Equation Of State ◽  
Fluid Distribution ◽  
Anisotropic Fluid ◽  
Spherically Symmetric ◽  
Polytropic Equation

scholarly journals Study of generalized cylindrical polytropes with complexity factor

2021 ◽  
Vol 81 (9) ◽  
Author(s):  
Shiraz Khan ◽  
S. A. Mardan ◽  
M. A. Rehman
Keyword(s):  
Equation Of State ◽  
Energy Density ◽  
Differential Equations ◽  
Mass Density ◽  
Modify Form ◽  
Graphical Analysis ◽  
Fluid Distribution ◽  
Anisotropic Fluid ◽  
Polytropic Equation ◽  
Frame Work

AbstractIn this paper, complexity factor is used with generalized polytropic equation of state to develop two consistent systems of three differential equations and a general frame work is established for modify form of Lane-Emden equations. For this purpose anisotropic fluid distribution is considered in cylindrical static symmetry with two cases of generalized polytropic equation of state (i) mass density $$\mu _{o}$$ μ o and (ii) energy density $$\mu $$ μ . A graphical analysis will be carried out for the numerical solution of these systems of three differential equations.

Cracking in anisotropic polytropic models

2018 ◽  
Vol 33 (24) ◽  
pp. 1850139
Author(s):  
M. Sharif ◽  
Sobia Sadiq
Keyword(s):  
Distribution Function ◽  
Equation Of State ◽  
Anisotropic Fluid ◽  
Polytropic Index ◽  
Force Distribution ◽  
Spherically Symmetric ◽  
Field Equations ◽  
Polytropic Equation ◽  
Density Perturbations ◽  
Fluid Configuration

This paper is devoted to examine the cracking of spherically symmetric anisotropic fluid configuration for polytropic equation of state. For this purpose, we formulate the corresponding field equations as well as generalized Tolman–Oppenheimer–Volkoff equation. We introduce density perturbations in matter variables and then construct the force distribution function. In order to examine the occurrence of cracking/overturning, we consider two models corresponding to two values of the polytropic index. It is found that the first model exhibits overturning for the considered values of polytropic constant while the second model neither exhibits cracking nor overturning for larger values of polytropic constant.

Stability of generalized polytropic models

2019 ◽  
Vol 16 (04) ◽  
pp. 1950056
Author(s):  
I. Nazir ◽  
M. Azam
Keyword(s):  
Equation Of State ◽  
Local Density ◽  
Hydrostatic Equilibrium ◽  
Physical Parameters ◽  
Spherically Symmetric ◽  
Anisotropic Matter ◽  
Polytropic Equation ◽  
Density Perturbations ◽  
Radial Forces ◽  
The Stability

In this paper, we have investigated the stability of a spherically symmetric object with charged anisotropic matter by using the concept of cracking. The cracking is a very intuitive technique to check the stability which is based on the analysis of the radial forces that appear on the system due to perturbations taking it out of its equilibrium state. For this, we have applied and studied the effect of local density perturbations to the hydrostatic equilibrium equation and on all the physical parameters with generalized polytropic equation of state. It is found that some of the generalized polytropic models exhibit cracking.

scholarly journals Framework for generalized polytropes with complexity factor

2019 ◽  
Vol 79 (12) ◽  
Author(s):  
Shiraz Khan ◽  
S. A. Mardan ◽  
M. A. Rehman
Keyword(s):  
Equation Of State ◽  
Energy Density ◽  
Differential Equations ◽  
Spherical Symmetry ◽  
Mass Density ◽  
Fluid Distribution ◽  
System Of Differential Equations ◽  
Systems Of Differential Equations ◽  
Polytropic Equation

AbstractA framework is developed for generalized polytropes with the help of complexity factor introduced by Herrera (Phy Rev D 97:044010, 2018), by using the spherical symmetry with anisotropic inner fluid distribution. For this purpose generalized polytropic equation of state will be used, having two cases (i) for mass density $$(\mu _{o})$$(μo), (ii) for energy density $$(\mu )$$(μ), each case leads to a system of differential equations. These systems of differential equations involve two equations with three unknowns and they will be made consistent by using the complexity factor. The analysis of the solutions of these systems will be carried out graphically by using different parametric values involved in the systems.

Study of conformally flat polytropes with tilted congruence

2018 ◽  
Vol 27 (07) ◽  
pp. 1850063 ◽  
Author(s):  
M. Sharif ◽  
Sobia Sadiq
Keyword(s):  
Equation Of State ◽  
Matter Content ◽  
Energy Conditions ◽  
Spherically Symmetric ◽  
Conformally Flat ◽  
Flat Condition ◽  
Polytropic Equation ◽  
Dissipative Fluid ◽  
Symmetric Spacetime ◽  
Fluid Configuration

This paper is aimed to study the modeling of spherically symmetric spacetime in the presence of anisotropic dissipative fluid configuration. This is accomplished for an observer moving relative to matter content using two cases of polytropic equation-of-state under conformally flat condition. We formulate the corresponding generalized Tolman–Oppenheimer–Volkoff equation, mass equation, as well as energy conditions for both cases. The conformally flat condition is imposed to find an expression for anisotropy which helps to study spherically symmetric polytropes. Finally, Tolman mass is used to analyze stability of the resulting models.

scholarly journals Impact of generalized polytropic equation of state on charged anisotropic polytropes

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
S. A. Mardan ◽  
M. Rehman ◽  
I. Noureen ◽  
R. N. Jamil
Keyword(s):  
Equation Of State ◽  
Speed Of Sound ◽  
Graphical Analysis ◽  
Maxwell Field ◽  
Anisotropic Fluid ◽  
Polytropic Index ◽  
Model Parameters ◽  
Field Equations ◽  
Polytropic Equation ◽  
Fluid Configuration

Abstract In this paper, generalized polytropic equation of state is used to get new classes of polytropic models from the solution of Einstein-Maxwell field equations for charged anisotropic fluid configuration. The models are developed for different values of polytropic index $$n=1,~\frac{1}{2},~2$$n=1,12,2. Masses and radii of eight different stars have been regained with the help of developed models. The speed of sound technique and graphical analysis of model parameters is used for the viability of developed models. The analysis of models indicates they are well behaved and physically viable.

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.

scholarly journals Dark Energy Stars with Quadratic Equation of State

2019 ◽  
Author(s):  
Manuel Malaver ◽  
Hamed Kasmaei
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Condition ◽  
Scalar Fields ◽  
Quadratic Equation ◽  
Accelerated Expansion ◽  
Fluid Distribution ◽  
Anisotropic Fluid ◽  
Field Equations ◽  
Quadratic Equation Of State

Recent astronomical observations with respect to measurements in distant supernovas, cosmic microwave background and weak gravitational lensing confirm that the Universe is undergoing a phase of accelerated expansion and it has been proposed that this cosmological behavior is caused by a hypothetical dark energy which has a strong negative pressure that allows explain the expanding universe. Several theoretical ideas and models related dark the energy includes the cosmological constant, quintessence, Chaplygin gas, braneworld and tachyonic scalar fields. In this paper, we have obtained new relativistic stellar configurations considering an anisotropic fluid distribution with a charge distribution which could represents a potential model of a dark energy star. In order to investigate the effect of a quadratic equation of state in this anisotropic model we specify particular forms for the gravitational potential that allow solving the Einstein-Maxwell field equations. For these new solutions we checked that the radial pressure, metric coefficients, energy density, anisotropy factor, charge density , mass function are well defined and are regular in the interior of the star. The solutions found can be used in the development of dark energy stars models satisfying all physical acceptability conditions but the causality condition and strong energy condition are violated. We expect that these models have multiple applications in astrophysics and cosmology.

Relativistic anisotropic models for compact star with equation of state p = f(ρ)

2017 ◽  
Vol 26 (02) ◽  
pp. 1750002 ◽  
Author(s):  
S. K. Maurya ◽  
Y. K. Gupta ◽  
Baiju Dayanandan ◽  
M. K. Jasim ◽  
Ahmed Al-Jamel
Keyword(s):  
Equation Of State ◽  
Compact Star ◽  
Fluid Distribution ◽  
Anisotropic Fluid ◽  
Perfect Fluid Solution ◽  
Anisotropic Models ◽  
Star Models ◽  
Astrophysical Objects ◽  
State Formula ◽  
The Stability

We present new anisotropic models for Buchdahl [H. A. Buchdahl, Phys. Rev. 116 (1959) 1027.] type perfect fluid solution. For this purpose, we started with metric potential [Formula: see text] same as Buchdahl [H. A. Buchdahl, Phys. Rev. 116 (1959) 1027.] and [Formula: see text] is monotonically increasing function as suggested by Lake [K. Lake, Phys. Rev. D 67 (2003) 104015]. After that we determine the new pressure anisotropy factor [Formula: see text] with the help of both the metric potentials [Formula: see text] and [Formula: see text] and propose new well behaved general solution for anisotropic fluid distribution. The physical quantities like energy density, radial and tangential pressures, velocity of sound and redshift etc. are positive and finite inside the compact star. In this connection, we have studied the stability of the models, which is most vital one and also we determined the equation of state [Formula: see text] for the realistic compact star models. It is noted that the mass and radius of our models can represent the structure of realistic astrophysical objects such as Her X-1 and RXJ 1856-37.

scholarly journals Star-plus-wormhole systems with two interacting scalar fields

2015 ◽  
Vol 24 (14) ◽  
pp. 1550097 ◽  
Author(s):  
Vladimir Dzhunushaliev ◽  
Vladimir Folomeev ◽  
Ajnur Urazalina
Keyword(s):  
Equation Of State ◽  
Scalar Fields ◽  
Spherically Symmetric ◽  
Fluid Density ◽  
Asymptotically Flat ◽  
Spacetime Topology ◽  
Polytropic Equation ◽  
General Relativistic

We study static, spherically symmetric mixed configurations with a nontrivial (wormhole) spacetime topology provided by the presence of two interacting ghost scalar fields. Wormhole is assumed to be filled by a perfect relativistic neutron fluid modeled by a polytropic equation of state. For such mixed configurations, we find regular, asymptotically flat general relativistic solutions. It is shown that the maximum of the fluid density is always shifted from the center and the resulting configurations represent, in general, double-throat systems.

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