scholarly journals An Exact Model of an Anisotropic Relativistic Sphere

1995 ◽  
Vol 48 (4) ◽  
pp. 635 ◽  
Author(s):  
LK Patel ◽  
NP Mehta
Keyword(s):  
Exact Solution ◽  
General Relativity ◽  
Fluid Sphere ◽  
Anisotropic Fluid ◽  
Physical Parameters ◽  
Field Equations ◽  
Exterior Solution ◽  
Exact Model ◽  
Anisotropic Fluid Sphere

In this paper the field equations of general relativity are solved to obtain an exact solution for a static anisotropic fluid sphere. The solution is free from singularity and satisfies the necessary physical requirements. The physical 3-space of the solution is pseudo-spheroidal. The solution is matched at the boundary with the Schwarzschild exterior solution. Numerical estimates of various physical parameters are briefly discussed.

scholarly journals Modelling of a compact anisotropic star as an anisotropic fluid sphere in f(T) gravity

2018 ◽  
Vol 96 (12) ◽  
pp. 1295-1303 ◽  
Author(s):  
D. Momeni ◽  
G. Abbas ◽  
S. Qaisar ◽  
Zaid Zaz ◽  
R. Myrzakulov
Keyword(s):  
Anisotropic Fluid ◽  
Physical Parameters ◽  
Parametric Form ◽  
Dynamical Equations ◽  
Strange Stars ◽  
Exact Model ◽  
Anisotropic Fluid Sphere ◽  
Metric Functions ◽  
Anisotropic Stars ◽  
Anisotropic Star

In this article, the authors have discussed a new exact model of anisotropic stars in the f(T) theory of gravity. A parametric form of the metric functions has been implemented to solve the dynamical equations in f(T) theory with the anisotropic fluid. The novelty of the work is that the obtained solutions do not contain singularity but are potentially stable. The estimated values for mass and radius of the different strange stars, RX J 1856–37, Her X-1, and Vela X-12, have been utilized to find the values of unknown constants in Krori and Barua metrics. The physical parameters like anisotropy, stability, and redshift of the stars have been examined in detail.

scholarly journals NONUNIFORM BRANEWORLD STARS: AN EXACT SOLUTION

2009 ◽  
Vol 18 (05) ◽  
pp. 837-852 ◽  
Author(s):  
J. OVALLE
Keyword(s):  
Exact Solution ◽  
Effective Density ◽  
Interior Solution ◽  
Effective Pressure ◽  
Gravity Effect ◽  
Field Equations ◽  
Matching Conditions ◽  
Physical Behavior ◽  
Exterior Solution ◽  
Weyl Scalar

In this paper the first exact interior solution to Einstein's field equations for a static and nonuniform braneworld star with local and nonlocal bulk terms is presented. It is shown that the bulk Weyl scalar [Formula: see text] is always negative inside the stellar distribution, and in consequence it reduces both the effective density and the effective pressure. It is found that the anisotropy generated by bulk gravity effect has an acceptable physical behavior inside the distribution. Using a Reissner–Nördstrom-like exterior solution, the effects of bulk gravity on pressure and density are found through matching conditions.

Color-flavor locked compact stars: An exact solution approach

2021 ◽  
Author(s):  
Ksh. Newton Singh ◽  
Shyam Das ◽  
Piyali Bhar ◽  
Monsur Rahaman ◽  
Farook Rahaman
Keyword(s):  
Exact Solution ◽  
Compact Star ◽  
Density Perturbation ◽  
Compact Stars ◽  
Stable Configuration ◽  
Physical Parameters ◽  
Superconducting Gap ◽  
Field Equations ◽  
Critical Limit ◽  
Solution Approach

We present an exact solution that could describe compact star composed of color-flavor locked (CFL) phase. Einstein’s field equations were solved through CFL equation of state (EoS) along with a specific form of [Formula: see text] metric potential. Further, to explore a generalized solution we have also included pressure anisotropy. The solution is then analyzed by varying the color superconducting gap [Formula: see text] and its effects on the physical parameters. The stability of the solution through various criteria is also analyzed. To show the physical validity of the obtained solution we have generated the [Formula: see text] curve and fitted three well-known compact stars. This work shows that the anisotropy of the pressure at the interior increases with the color superconducting gap leading to decrease in adiabatic index closer to the critical limit. Further, the fluctuating range of mass due to the density perturbation is larger for lower color superconducting gap leading to more stable configuration.

Exact solution of a static charged sphere in general relativity

1969 ◽  
Vol 47 (21) ◽  
pp. 2401-2404 ◽  
Author(s):  
S. J. Wilson
Keyword(s):  
Exact Solution ◽  
General Relativity ◽  
Gravitational Constant ◽  
The Self ◽  
Spherically Symmetric ◽  
Charged Sphere ◽  
Field Equations ◽  
First Order ◽  
Self Energy ◽  
Spherically Symmetric Distribution

An exact solution of the field equations of general relativity is obtained for a static, spherically symmetric distribution of charge and mass which can be matched with the Reissner–Nordström metric at the boundary. The self-energy contributions to the total gravitational mass are computed retaining only the first order terms in the gravitational constant.

scholarly journals Mimicking static anisotropic fluid spheres in general relativity

2016 ◽  
Vol 25 (02) ◽  
pp. 1650019 ◽  
Author(s):  
Petarpa Boonserm ◽  
Tritos Ngampitipan ◽  
Matt Visser
Keyword(s):  
Electromagnetic Field ◽  
Scalar Field ◽  
Charge Density ◽  
Perfect Fluid ◽  
Radial Pressure ◽  
Energy Conditions ◽  
Fluid Sphere ◽  
Anisotropic Fluid ◽  
Spherically Symmetric ◽  
Anisotropic Fluid Sphere

We argue that an arbitrary general relativistic static anisotropic fluid sphere, (static and spherically symmetric but with transverse pressure not equal to radial pressure), can nevertheless be successfully mimicked by suitable linear combinations of theoretically attractive and quite simple classical matter: a classical (charged) isotropic perfect fluid, a classical electromagnetic field and a classical (minimally coupled) scalar field. While the most general decomposition is not unique, a preferred minimal decomposition can be constructed that is unique. We show how the classical energy conditions for the anisotropic fluid sphere can be related to energy conditions for the isotropic perfect fluid, electromagnetic field, and scalar field components of the model. Furthermore, we show how this decomposition relates to the distribution of both electric charge density and scalar charge density throughout the model. The generalized TOV equation implies that the perfect fluid component in this model is automatically in internal equilibrium, with pressure forces, electric forces, and scalar forces balancing the gravitational pseudo-force. Consequently, we can build theoretically attractive matter models that can be used to mimic almost any static spherically symmetric spacetime.

General relativistic fluid spheres with variable polytropic index

1966 ◽  
Vol 6 (2) ◽  
pp. 139-147
Author(s):  
R. van der Borght
Keyword(s):  
General Relativity ◽  
Compressible Fluid ◽  
Fluid Sphere ◽  
Polytropic Index ◽  
Field Equations ◽  
Relativistic Fluid ◽  
General Relativistic ◽  
Temperature And Pressure ◽  
Fluid Spheres

AbstractIn this paper we derive solutions of the field equations of general relativity for a compressible fluid sphere which obeys density-temperature and pressure-temperature relations which allow for a variation of the polytropic index throughout the sphere.

scholarly journals Einsteinian Gravitational Field of a Heterogeneous Fluid Sphere

1925 ◽  
Vol 44 ◽  
pp. 72-78
Author(s):  
Jyotirmaya Ghosh
Keyword(s):  
Differential Equation ◽  
Exact Solution ◽  
Empty Space ◽  
Variable Coefficients ◽  
Fluid Sphere ◽  
Uniform Density ◽  
Large Radius ◽  
Field Equations ◽  
Linear Differential ◽  
Gravitational Equations

The field-equations of gravitation in Einstein's theory have been solved in the case of an empty space, giving rise to de Sitter's spherical world. In the case of homogeneous matter filling all space, the solution gives Einstein's cylindrical world. The field corresponding to an isolated particle has been obtained by Schwarzchild. He has also obtained a solution for a fluid sphere with uniform density, a problem treated also by Nordström and de Donder. A new solution of the gravitational equations has been obtained in this paper, which corresponds to the field of a heterogeneous fluid sphere, the density at any point being a certain function of the distance of the point from the centre. The law of density is quite simple and such as to give finite density at the centre and gradually diminishing values as the distance from the centre increases, as might be expected of a natural sphere of fluid of large radius. The general problem of the fluid sphere with any arbitrary law of density cannot be solved in exact terms. It will be seen, however, from a theorem obtained in this paper, that the solution depends on a linear differential equation of the second order with variable coefficients involving the density, and thus the laws of density for which the problem admits of exact solution are those for which the above coefficients satisfy the conditions of integrability of the differential equation. An approximate solution for any law of density may be obtained by the method of series.

scholarly journals Bianchi type-V cosmology with magnetized anisotropic dark energy

2017 ◽  
Vol 95 (3) ◽  
pp. 274-282
Author(s):  
M. Farasat Shamir ◽  
Asad Ali
Keyword(s):  
Magnetic Field ◽  
Dark Energy ◽  
Bianchi Type ◽  
Anisotropic Fluid ◽  
Physical Parameters ◽  
Anisotropic Universe ◽  
Field Equations ◽  
Constant Deceleration Parameter ◽  
Type V ◽  
Bianchi Type V

We study anisotropic universe in the presence of magnetized dark energy. Bianchi type-V cosmological model is considered for this purpose. The energy–momentum tensor consists of anisotropic fluid with uniform magnetic field of energy density ρB. Exact solutions to the field equations are obtained without using conventional assumptions like constant deceleration parameter. In particular, a general solution is obtained that further provides different classes of solutions. Only three cases have been discussed for the present analysis: linear, quadratic, and exponential. Graphical analyses of the solutions are done for all the three classes. The behavior of the model using some important physical parameters is discussed in the presence of magnetic field.

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