scholarly journals Structure scalars and their evolution for massive objects in f(R) gravity

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
M. Z. Bhatti ◽  
Z. Yousaf ◽  
Z. Tariq
Keyword(s):  
Riemann Tensor ◽  
Spherically Symmetric ◽  
Density Inhomogeneity ◽  
Structure Scalars ◽  
Composition And Structure ◽  
Pressure Anisotropy ◽  
Spherically Symmetric Solutions ◽  
Astrophysical Objects ◽  
Energy Density Inhomogeneity ◽  
Insight Into

AbstractIn this manuscript, the Riemann tensor is split orthogonally to get five scalar functions known as structure scalars which have significance to gain insight into the composition and structure of spherically symmetric self-gravitating objects. Certain stellar equations are then evaluated to gather information about physical characteristics of such astrophysical objects. These stellar equations are further written in terms of acquired structure scalars so that the basic properties such as pressure anisotropy and energy density inhomogeneity of the fluid under consideration can be explored. Also, we have explored few static spherically symmetric solutions to show significance of structure scalars in the background of f(R) gravity.

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 Influence of modification of gravity on the complexity factor of static spherical structures

2020 ◽  
Vol 495 (4) ◽  
pp. 4334-4346
Author(s):  
Z Yousaf ◽  
Maxim Yu Khlopov ◽  
M Z Bhatti ◽  
T Naseer
Keyword(s):  
Gravitational Theory ◽  
Momentum Tensor ◽  
Matter Distribution ◽  
Field Equations ◽  
Riemann Curvature Tensor ◽  
Structure Scalars ◽  
Pressure Anisotropy ◽  
Spherical Structures ◽  
Energy Density Inhomogeneity ◽  
Definition Of

ABSTRACT The aim of this paper is to generalize the definition of complexity for the static self-gravitating structure in f (R, T, Q) gravitational theory, where R is the Ricci scalar, T is the trace part of energy–momentum tensor, and Q ≡ RαβT αβ. In this context, we have considered locally anisotropic spherical matter distribution and calculated field equations and conservation laws. After the orthogonal splitting of the Riemann curvature tensor, we found the corresponding complexity factor with the help of structure scalars. It is seen that the system may have zero complexity factor if the effects of energy density inhomogeneity and pressure anisotropy cancel the effects of each other. All of our results reduce to general relativity on assuming f (R, T, Q) = R condition.

Stellar systems and structure scalars

2019 ◽  
Vol 97 (5) ◽  
pp. 465-471 ◽  
Author(s):  
S. Ahmad ◽  
A. Rehman Jami ◽  
I. Ahmad ◽  
H. Sadia
Keyword(s):  
Riemann Tensor ◽  
Matter Content ◽  
Anisotropic Pressure ◽  
Energy Tensor ◽  
Spherically Symmetric ◽  
Structure Scalars ◽  
Tidal Forces ◽  
Stress Energy ◽  
Symmetric Geometry

The work is devoted to analyzing the effects of dark source polynomial curvature corrections in the mathematical modeling of radiating stars. In this scenario, we have used a particular f(R, T) model and consider the spherically symmetric geometry of relativistic interior. We assumed that our geometry is coupled with anisotropic shearing matter distribution undergoing radiating epoch with free streaming and diffusion approximation. We have calculated spherically symmetric total matter content with the help of Misner–Sharp formalism. A particular relation among anisotropic pressure, shearing viscosity, radiating parameters, energy density, and tidal forces is obtained. We then expressed this equation with the help of f(R, T) structure scalar, the scalar obtained by orthogonal decomposition of the Riemann tensor. The role of the logarithmic Ricci and trace of stress–energy tensor terms are also observed through Weyl scalar, shear, expansion scalar differential equations.

Evolution of axially symmetric systems and f(G) gravity

2017 ◽  
Vol 26 (10) ◽  
pp. 1750109 ◽  
Author(s):  
M. Sharif ◽  
H. Ismat Fatima
Keyword(s):  
Transport Equation ◽  
Heat Transport ◽  
Heat Dissipation ◽  
Axially Symmetric ◽  
Density Inhomogeneity ◽  
Thermodynamic Aspect ◽  
Structure Scalars ◽  
Pressure Anisotropy ◽  
Heat Transport Equation ◽  
Symmetric Systems

This paper explores evolution of dissipative axially symmetric collapsing fluid under the dark effects of [Formula: see text] gravity. We formulate the dynamical variables and study the effects of dark sources in pressure anisotropy as well as heat dissipation. The structure scalars (scalar functions) as well as their role in the dynamics of source are investigated. Finally, we develop heat transport equation to examine the thermodynamic aspect and a set of equations governing the evolution of dynamical variables. It is concluded that dark sources affect thermodynamics of the system, evolution of kinematical quantities as well as density inhomogeneity.

scholarly journals FERMIONS IN THE BACKGROUND OF DILATONIC SPHALERONS

1994 ◽  
Vol 09 (40) ◽  
pp. 3731-3739 ◽  
Author(s):  
GEORGE LAVRELASHVILI
Keyword(s):  
Gauge Field ◽  
Field Potential ◽  
Spherically Symmetric ◽  
Yang Mills ◽  
Zero Modes ◽  
Discrete Sequence ◽  
Number Of Zeros ◽  
Spherically Symmetric Solutions ◽  
Static Spherically Symmetric Solutions

We discuss the properties and interpretation of a discrete sequence of a static spherically symmetric solutions of the Yang-Mills dilaton theory. This sequence is parametrized by the number of zeros, n, of a component of the gauge field potential. It is demonstrated that solutions with odd n possess all the properties of the sphaleron. It is shown that there are normalizable fermion zero modes in the background of these solutions. The question of instability is critically analyzed.

scholarly journals Intersecting Electric and Magnetic p-branes: Spherically Symmetric Solutions

1999 ◽  
Vol 31 (11) ◽  
pp. 1681-1702 ◽  
Author(s):  
K. A. Bronnikov ◽  
U. Kasper ◽  
M. Rainer
Keyword(s):  
Spherically Symmetric ◽  
Spherically Symmetric Solutions
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