Spherically symmetric self-gravitating radiating star under expansion-free motion

2020 ◽  
Vol 17 (13) ◽  
pp. 2050189
Author(s):  
Rajesh Kumar ◽  
S. K. Srivastava
Keyword(s):  
Diffusion Approximation ◽  
Energy Condition ◽  
Free Motion ◽  
Fluid Distribution ◽  
Spherically Symmetric ◽  
Dynamical Equations ◽  
Fundamental Properties ◽  
Structure Scalars ◽  
Perfect Fluids ◽  
Radiating Star

This study deals with the spherically symmetric radiating star (with dissipative perfect fluids) with a central vacuum cavity, evolving under the assumption of expansion-free motion. The analytical model of the such dynamics star is discussed in three regimes — diffusion approximation, geodesic motion and self-similarity — and the solutions of dynamical equations are obtained in its complete generality. The structure scalars, which are related to the fundamental properties of fluid distribution, are also discussed which played a very important role in the dynamics of cavity models. It has been shown that energy density is homogeneous but violates the energy condition under quasi-static diffusion approximation.

Complexity analysis of dynamical spherically-symmetric dissipative self-gravitating objects in modified gravity

2020 ◽  
Vol 29 (02) ◽  
pp. 2050014
Author(s):  
M. Zubair ◽  
Hina Azmat
Keyword(s):  
Complexity Analysis ◽  
Fluid Distribution ◽  
Anisotropic Fluid ◽  
Spherically Symmetric ◽  
Evolutionary Patterns ◽  
Structure Scalars ◽  
Pressure Anisotropy ◽  
Energy Density Inhomogeneity ◽  
Expansion Condition ◽  
Definition Of

In this paper, we have worked on the concept of complexity factor for nonstatic spherically-symmetric self-gravitating source filled with anisotropic fluid distribution in [Formula: see text] gravity theory. The definition of complexity for dynamical sources, proposed by Herrera, is examined in the framework of [Formula: see text] gravity. We intended to analyze the behavior of complexity factor in modified theory. For this, we defined the scalar functions through orthogonal splitting of Reimann tensor in [Formula: see text] gravity and worked out the structure scalars. We considered the structure scalar [Formula: see text] as a complexity factor to evaluate the complexity of the structure of dynamical system and also to analyze the complexity of the evolutionary patterns of the system under consideration. We took into account the homologous condition and homogeneous expansion condition in order to present the simplest mode of evolution, and found that homologous evolution is the simplest one. We considered both dissipative and nondissipative cases and found that shearing behavior of the fluid is not the same in both cases, however it remained geodesic in both cases. In the end, we established the results for the vanishing of the complexity factor. It has been found that zero complexity condition is satisfied if the energy density inhomogeneity and pressure anisotropy of the fluid configuration cancel each other.

scholarly journals Role of f(G) Gravity in the Study of Non-Static Complex Systems

2021 ◽  
Author(s):  
Z. Yousaf ◽  
M.Z. Bhatti ◽  
M. M. M. Nasir
Keyword(s):  
Fluid Distribution ◽  
Free Fluid ◽  
Spherically Symmetric ◽  
Static Case ◽  
Structure Scalars ◽  
System A ◽  
Wide Range ◽  
Dissipative Case ◽  
Isotropic Geodesic ◽  
The Stability

The concept of complexity for dynamical spherically symmetric dissipative self-gravitating configuration [1] is generalized in the scenario of modified Gauss-Bonnet gravity. For this purpose, a spherically symmetric fluid with locally anisotropic, dissipative, and non-dissipative configuration is considered. We choose the same complexity factor for the structure as we did for the static case, while we consider the homologous condition for the simplest pattern of evolution. In this approach, we formulate structure scalars that demonstrate the essential properties of the system. A fluid distribution that fulfills the vanishing complexity constraint and proceeds homologously corresponds to isotropic, geodesic, homogeneous, and shear-free fluid. In the dissipative case, the fluid is still geodesic but it is shearing, and there is a wide range of solutions. In the last, the stability of vanishing complexity is examined.

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.

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.

Complexity factor for dynamical spherically symmetric fluid distributions in f(R) gravity

2019 ◽  
Vol 16 (11) ◽  
pp. 1950170
Author(s):  
H. Nazar ◽  
G. Abbas
Keyword(s):  
Physical Nature ◽  
The Self ◽  
Fluid Distribution ◽  
Spherically Symmetric ◽  
Static Case ◽  
System Configuration ◽  
Prior Investigation ◽  
Text Model ◽  
The Stability ◽  
Stability Results

In this study, we analyze the complexity factor that is extended up to the dynamical spherically symmetric non-static case with anisotropic dissipative self-gravitating fluid distribution in context of [Formula: see text] theory of gravity. For this evaluation we choose the particular [Formula: see text] model that signifies the physical nature of the self-gravitating system. The proposed work discusses not only the complexity factor of the structure of the fluid distribution, but also defines the minimization rate of complexity of the pattern of evolution. Here, first we have applied similar approach for obtaining the structure scalar [Formula: see text] of the complexity factor as used for in the static case, and next we have described explicitly the dissipative and non-dissipative cases by assuming the simplest pattern of evolution (homologous condition). It has been found that the system configuration fulfills the vanishing condition of complexity factor and emerging homologously, corresponds to a energy density homogeneity, shearfree and geodesic, isotropic in pressure. Moreover, we define the stability results for the vanishing complexity factor condition. Finally, we would like to mention that these results are satisfying the prior investigation about complexity factor in General Relativity (GR) by setting [Formula: see text].

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 On the Energy of a Non-Singular Black Hole Solution Satisfying the Weak Energy Condition

Universe ◽  
2020 ◽  
Vol 6 (10) ◽  
pp. 169
Author(s):  
Irina Radinschi ◽  
Theophanes Grammenos ◽  
Farook Rahaman ◽  
Marius-Mihai Cazacu ◽  
Andromahi Spanou ◽  
...  
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Energy Distribution ◽  
Black Hole Solution ◽  
Energy Condition ◽  
Weak Energy Condition ◽  
Radial Coordinate ◽  
Spherically Symmetric ◽  
Comparison Of The Results ◽  
Two Parameters

The energy-momentum localization for a new four-dimensional and spherically symmetric, charged black hole solution that through a coupling of general relativity with non-linear electrodynamics is everywhere non-singular while it satisfies the weak energy condition, is investigated. The Einstein and Møller energy-momentum complexes have been employed in order to calculate the energy distribution and the momenta for the aforesaid solution. It is found that the energy distribution depends explicitly on the mass and the charge of the black hole, on two parameters arising from the space-time geometry considered, and on the radial coordinate. Further, in both prescriptions all the momenta vanish. In addition, a comparison of the results obtained by the two energy-momentum complexes is made, whereby some limiting and particular cases are pointed out.

scholarly journals Evolution of thin shells in D-dimensional general relativity

2019 ◽  
Vol 28 (04) ◽  
pp. 1950069 ◽  
Author(s):  
Marcos A. Ramirez ◽  
Daniel Aparicio
Keyword(s):  
Energy Condition ◽  
Cosmic Censorship ◽  
Einstein Equations ◽  
Thin Shells ◽  
Dominant Energy Condition ◽  
Spherically Symmetric ◽  
Barotropic Fluids ◽  
Large Shell ◽  
Asymptotic Dynamics ◽  
Electrovacuum Solution

In this paper, we consider singular timelike spherical hypersurfaces embedded in a [Formula: see text]-dimensional spherically symmetric bulk spacetime which is an electrovacuum solution of Einstein equations with cosmological constant. We analyze the different possibilities regarding the orientation of the gradient of the standard [Formula: see text] coordinate in relation to the shell. Then we study the dynamics according to Einstein equations for arbitrary matter satisfying the dominant energy condition. In particular, we thoroughly analyze the asymptotic dynamics for both the small and large-shell-radius limits. We also study the main qualitative aspects of the dynamics of shells made of linear barotropic fluids that satisfy the dominant energy condition. Finally, we prove weak cosmic censorship for this class of solutions.

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