Gravitational Collapse For Anisotropic Radiating Star With Karmarkar Condition in f(R,T) Gravity

2021 ◽  
Author(s):  
Riaz Ahmed ◽  
G. Abbas ◽  
Ertan Güdekli
Keyword(s):  
Gravitational Collapse ◽  
Radiating Star

NON-ADIABATIC GRAVITATIONAL COLLAPSE OF A SUPERDENSE STAR

2010 ◽  
Vol 19 (12) ◽  
pp. 1889-1904 ◽  
Author(s):  
SANJAY SARWE ◽  
RAMESH TIKEKAR
Keyword(s):  
Black Hole ◽  
Heat Flow ◽  
Gravitational Collapse ◽  
Adiabatic Shear ◽  
Dissipative Forces ◽  
Superdense Stars ◽  
Superdense Star ◽  
Radiating Star ◽  
Spheroidal Geometry ◽  
Relativistic Equations

The relativistic equations governing the non-adiabatic shear-free collapse of massive superdense stars in the presence of dissipative forces producing heat flow in the background of space–times of the Vaidya–Tikekar ansatz with associated physical three-spaces that have the three-spheroidal geometry are formulated. It is shown how the system can be used to examine the development and progress of the collapse during subsequent epochs until the radiating star becomes a black hole.

RADIATING GRAVITATIONAL COLLAPSE WITH SHEAR VISCOSITY AND BULK VISCOSITY

2004 ◽  
Vol 13 (08) ◽  
pp. 1727-1752 ◽  
Author(s):  
P. C. NOGUEIRA ◽  
R. CHAN
Keyword(s):  
Heat Flow ◽  
Viscous Fluid ◽  
Gravitational Collapse ◽  
Bulk Viscosity ◽  
Shear Viscosity ◽  
Outgoing Radiation ◽  
Radial Heat Flow ◽  
Radial Heat ◽  
Radiating Star ◽  
Time Density

A model of a collapsing radiating star consisting of a fluid with shear viscosity and bulk viscosity undergoing radial heat flow with outgoing radiation is studied. This kind of fluid is the most general viscous fluid we can have. The pressure of the star, at the beginning of the collapse, is isotropic but, due to the presence of the shear viscosity and the bulk viscosity, the pressure becomes more and more anisotropic. The radial and temporal behaviors of the density, pressure, mass, luminosity, the effective adiabatic index and the Kretschmann scalar are analyzed. The collapsing time, density, mass, luminosity and Kretschmann scalar of the star do not depend on the viscosity of the fluid (nor the shear viscosity and neither the bulk viscosity).

scholarly journals A perturbative approach to the time-dependent Karmarkar condition

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
Megandhren Govender ◽  
Wesley Govender ◽  
Kevin P Reddy ◽  
Sunil D Maharaj
Keyword(s):  
Boundary Condition ◽  
Heat Flux ◽  
Gravitational Collapse ◽  
Time Dependent ◽  
Perturbative Approach ◽  
Radial Heat ◽  
Radiating Star ◽  
Static Regime ◽  
Radial Heat Flux ◽  
Static Core

AbstractIn this work we employ a perturbative approach to study the gravitational collapse of a shear-free radiating star. The collapse proceeds from an initial static core satisfying the time-independent Karmarkar condition and degenerates into a quasi-static regime with the generation of energy in the form of a radial heat flux. The time-dependent Karmarkar condition is solved together with the boundary condition to yield the full gravitational behaviour of the star. Our model is subjected to rigorous regularity, causality and stability tests.

Non-adiabatic gravitational collapse in f(R,T) gravity with Karmarkar condition for anisotropic fluid

2020 ◽  
Vol 35 (13) ◽  
pp. 2050103 ◽  
Author(s):  
Riaz Ahmed ◽  
G. Abbas
Keyword(s):  
Gravitational Collapse ◽  
Coupling Parameter ◽  
Momentum Tensor ◽  
Energy Conditions ◽  
Anisotropic Fluid ◽  
Interior Solution ◽  
Spatial Presence ◽  
Field Equations ◽  
Gravitational Field Equations ◽  
Radiating Star

In this paper, we have used the Karmarkar condition to the spherically symmetric non-static radiating star experiencing dissipative gravitational collapse with a heat flux in the framework of [Formula: see text] gravity, (where [Formula: see text] is Ricci scalar which replaces Lagrangian density and [Formula: see text] is the trace of energy–momentum tensor). To obtain the ultimate results of the gravitational field equations in [Formula: see text] scenario, we take a linear form of the function as [Formula: see text]. In this connection, the Karmarkar condition along with boundary condition generates a model of radiating star and enables us to completely indicate the spatial presence of gravitational potentials. Vadiya’s exterior solution across a time-like hypersurface is smoothly matched to the interior solution which allows to study the physical conduct of our model under consideration. Furthermore, we have analyzed the energy conditions of radiating star in [Formula: see text] gravity and analyzed the physical behavior of thermodynamics parameters which provide a detailed discussion of the model. For coupling parameter [Formula: see text], we successfully obtain the standard results of General Relativity.

scholarly journals Charged anisotropic spherical collapse with heat flow

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
Kali Charan ◽  
Om Prakash Yadav ◽  
B. C. Tewari
Keyword(s):  
Differential Equation ◽  
Ordinary Differential Equation ◽  
Gravitational Collapse ◽  
Energy Conditions ◽  
Junction Conditions ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Radiating Star ◽  
Large Round ◽  
High Degree

AbstractIn this article, we study the shear-free gravitational collapse of a charged radiating star. The Einstein field equations of gravitational collapse for the charged stars are known to give rise to a high degree of non-linearity in the ordinary differential equation coming from junction conditions. The attempts to solve it analytically proved to be unfortunate. Numerical methods have been suggested in the past. However, the high degree of non-linearity tends to introduce fluctuations and large round off errors in the numerical calculation. A new ansatz is proposed in the present work to reduce the degree of non-linearity. An ordinary differential equation is derived by satisfying junction conditions, and its numerical solution is demonstrated. Physical quantities associated with the collapse process are plotted to observe the effect of charge on these quantities. It is concluded that the charge can delay the collapse of a star and can even prevent it depending upon the amount of charge. It is also verified that the solution satisfies all the energy conditions.

Gravitational collapse of a radiating star

1989 ◽  
Vol 141 (5-6) ◽  
pp. 243-248 ◽  
Author(s):  
Charalampos Kolassis ◽  
Nilton O. Santos
Keyword(s):  
Gravitational Collapse ◽  
Radiating Star

RADIATING GRAVITATIONAL COLLAPSE WITH SHEAR REVISITED

2003 ◽  
Vol 12 (06) ◽  
pp. 1131-1155 ◽  
Author(s):  
R. CHAN
Keyword(s):  
Black Hole ◽  
Heat Flow ◽  
Gravitational Collapse ◽  
Total Mass ◽  
Naked Singularity ◽  
Radial Heat Flow ◽  
Radial Heat ◽  
Radiating Star ◽  
Shear Motion ◽  
Final Evolution

A model is proposed for a collapsing radiating star consisting of a fluid with shear motion undergoing radial heat flow with outgoing radiation. The pressure of the star, at the beginning of the collapse, is isotropic but due to the presence of the shear motion of the fluid the pressure becomes more and more anisotropic. The radial and temporal behaviors of the density, the pressure, the total mass, the luminosity, the effective adiabatic index and the Kretschmann scalar are analyzed for a star with 6 M⊙. The final evolution is a star that radiates all its mass during the collapse, and thus, neither forming a black hole, as in the previous model, nor a naked singularity.

Introduction

2018 ◽  
Author(s):  
Flavio Mercati
Keyword(s):  
Field Theory ◽  
General Relativity ◽  
Gravitational Collapse ◽  
Present State ◽  
Strong Gravity ◽  
Shape Dynamics

Shape Dynamics (SD) is a field theory that describes gravity in a different way than General Relativity (GR): it assumes a preferred notion of simultaneity, and the dynamical content of the theory consists of conformal 3- geometries. SD coincides with (GR) in most situations, in particular in the experimentally well-tested regimes, but it departs from it in some strong-gravity situations, for example at cosmological singularities or upon gravitational collapse. This chapter provides a quick introduction to the theory and a brief description of its present state.

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