scholarly journals Anisotropic Tolman VII solution by gravitational decoupling

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Sudipta Hensh ◽  
Zdeněk Stuchlík
Keyword(s):  
Perfect Fluid ◽  
Compact Objects ◽  
Effective Density ◽  
Fluid Solution ◽  
Coupling Constant ◽  
Tangential Pressure ◽  
Geometric Deformation ◽  
Two Fluid ◽  
Deformation Approach

Abstract Using the gravitational decoupling by the minimal geometric deformation approach, we build an anisotropic version of the well-known Tolman VII solution, determining an exact and physically acceptable interior two-fluid solution that can represent behavior of compact objects. Comparison of the effective density and density of the perfect fluid is demonstrated explicitly. We show that the radial and tangential pressure are different in magnitude giving thus the anisotropy of the modified Tolman VII solution. The dependence of the anisotropy on the coupling constant is also shown.

scholarly journals Minimal geometric deformation in a Reissner–Nordström background

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Ángel Rincón ◽  
Luciano Gabbanelli ◽  
Ernesto Contreras ◽  
Francisco Tello-Ortiz
Keyword(s):  
Black Hole Solution ◽  
Effective Density ◽  
Schwarzschild Black Hole ◽  
Exact Analytical Solutions ◽  
Geometric Deformation ◽  
New Material ◽  
Free Parameters ◽  
Scalar Invariants ◽  
Deformation Approach ◽  
Do So

Abstract This article is devoted to the study of new exact analytical solutions in the background of Reissner–Nordström space-time by using gravitational decoupling via minimal geometric deformation approach. To do so, we impose the most general equation of state, relating the components of the $$\theta $$θ-sector in order to obtain the new material contributions and the decoupler function f(r). Besides, we obtain the bounds on the free parameters of the extended solution to avoid new singularities. Furthermore, we show the finitude of all thermodynamic parameters of the solution such as the effective density $${\tilde{\rho }}$$ρ~, radial $${\tilde{p}}_{r}$$p~r and tangential $${\tilde{p}}_{t}$$p~t pressure for different values of parameter $$\alpha $$α and the total electric charge Q. Finally, the behavior of some scalar invariants, namely the Ricci R and Kretshmann $$R_{\mu \nu \omega \epsilon }R^{\mu \nu \omega \epsilon }$$RμνωϵRμνωϵ scalars are analyzed. It is also remarkable that, after an appropriate limit, the deformed Schwarzschild black hole solution always can be recovered.

scholarly journals Regularity condition on the anisotropy induced by gravitational decoupling in the framework of MGD

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
G. Abellán ◽  
V. A. Torres-Sánchez ◽  
E. Fuenmayor ◽  
E. Contreras
Keyword(s):  
Standard Method ◽  
Regularity Condition ◽  
Physical Characteristics ◽  
Compact Objects ◽  
Anisotropy Factor ◽  
Einstein Equations ◽  
Anisotropic Fluid ◽  
Acceptable Solution ◽  
Geometric Deformation ◽  
Deformation Approach

Abstract We use gravitational decoupling to establish a connection between the minimal geometric deformation approach and the standard method for obtaining anisotropic fluid solutions. Motivated by the relations that appear in the framework of minimal geometric deformation, we give an anisotropy factor that allows us to solve the quasi–Einstein equations associated to the decoupling sector. We illustrate this by building an anisotropic extension of the well known Tolman IV solution, providing in this way an exact and physically acceptable solution that represents the behavior of compact objects. We show that, in this way, it is not necessary to use the usual mimic constraint conditions. Our solution is free from physical and geometrical singularities, as expected. We have presented the main physical characteristics of our solution both analytically and graphically and verified the viability of the solution obtained by studying the usual criteria of physical acceptability.

scholarly journals The Minimal Geometric Deformation Approach: A Brief Introduction

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
J. Ovalle ◽  
R. Casadio ◽  
A. Sotomayor
Keyword(s):  
Perfect Fluid ◽  
Brane World ◽  
Geometric Deformation ◽  
General Relativistic ◽  
Deformation Approach

We review the basic elements of the Minimal Geometric Deformation approach in detail. This method has been successfully used to generate brane-world configurations from general relativistic perfect fluid solutions.

scholarly journals Durgapal IV model considering the minimal geometric deformation approach

2020 ◽  
Vol 44 (10) ◽  
pp. 105102
Author(s):  
Francisco Tello-Ortiz ◽  
Ángel Rincón ◽  
Piyali Bhar ◽  
Y. Gomez-Leyton
Keyword(s):  
Geometric Deformation ◽  
Iv Model ◽  
Deformation Approach

DENSITY DEPENDENT STRONG COUPLING CONSTANT OF QCD DERIVED FROM COMPACT STAR DATA

2000 ◽  
Vol 15 (20) ◽  
pp. 1301-1306 ◽  
Author(s):  
SUBHARTHI RAY ◽  
JISHNU DEY ◽  
MIRA DEY
Keyword(s):  
Strong Coupling ◽  
Binary Stars ◽  
Compact Star ◽  
Strong Coupling Constant ◽  
Compact Objects ◽  
Coupling Constant ◽  
X Ray ◽  
Star Data ◽  
Quark Stars ◽  
Time Formalism

Since 1996 there is major influx of X-ray and γ-ray data from binary stars, one or both of which are compact objects that are difficult to explain as neutron stars since they contain a mass M in too small a radius R. The suggestion has been put forward that these are strange quark stars (SS) explainable in a simple model with chiral symmetry restoration (CSR) for the quarks and the M, R and other properties like QPOs (quasi-periodic oscillations) in their X-ray power spectrum. It would be nice if this astrophysical data could shed some light on fundamental properties of quarks obeying QCD. One can relate the strong coupling constant of QCD, αs to the quark mass through the Dyson–Schwinger gap equation using the real time formalism of Dolan and Jackiw. This enables us to obtain the density dependence of αs from the simple CSR referred to above. This way fundamental physics, difficult to extract from other models like for example lattice QCD, can be constrained from present-day compact star data and may be put back to modeling the dense quark phase of early universe.

scholarly journals The minimal geometric deformation approach extended

2015 ◽  
Vol 32 (21) ◽  
pp. 215020 ◽  
Author(s):  
R Casadio ◽  
J Ovalle ◽  
Roldão da Rocha
Keyword(s):  
Geometric Deformation ◽  
Deformation Approach

scholarly journals Accelerating Anisotropic Cosmological Model Filled with Two Fluid and ∧

2020 ◽  
Vol 9 (3) ◽  
pp. 1590-1592
Keyword(s):  
Cosmological Model ◽  
Cosmological Constant ◽  
Perfect Fluid ◽  
Cosmological Parameters ◽  
Anisotropic Cosmological Model ◽  
Shear Scalar ◽  
Two Fluid

In this paper we have studied Kantowski-Sachs universe filled with perfect fluid and radiation with a cosmological constant. To get determinate solution, it is assumed that the scalar of expansion is proportional to shear scalar (    ) which leads to the relation between metric potentials n R AS The cosmological parameters of models are also discussed.

scholarly journals Charged stars in 4D Einstein–Gauss–Bonnet gravity

2021 ◽  
Vol 81 (9) ◽  
Author(s):  
Ayan Banerjee ◽  
Sudan Hansraj ◽  
Lushen Moodly
Keyword(s):  
Graphical Analysis ◽  
Compact Objects ◽  
Gravity Theory ◽  
Compact Stars ◽  
Model Parameters ◽  
The Novel ◽  
Coupling Constant ◽  
Curvature Effects ◽  
New Exact Solutions ◽  
Local Gravity

AbstractAn alternative gravity theory that has attracted considerable attention recently is the novel four-dimensional Einstein–Gauss–Bonnet (4EGB) gravity. This idea was proposed to bypass the Lovelock’s theorem and to permit nontrivial higher curvature effects on the four-dimensional local gravity. In this approach, the Gauss–Bonnet (GB) coupling constant $$\alpha $$ α is rescaled by a factor of $$\alpha /(D -4)$$ α / ( D - 4 ) in D dimensions and taking the limit $$D \rightarrow 4$$ D → 4 . In this article, we analyze the effects of charge on static compact stars in the regularized 4D EGB gravity theory. Two classes of new exact solutions are found for a particular choice of the gravitational potential and assuming a relationship between the electric field intensity and the spatial potential. A graphical analysis indicates that the matter and electromagnetic variables are well behaved for specific values of the parameter space. Finally, based on physical grounds appropriate bounds on the model parameters we show that compact objects with the value of adiabatic index $$\gamma $$ γ is consistent with expectations.

scholarly journals Ultracompact stars with polynomial complexity by gravitational decoupling

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
M. Carrasco-Hidalgo ◽  
E. Contreras
Keyword(s):  
Differential Equations ◽  
Polynomial Complexity ◽  
System Of Differential Equations ◽  
Geometric Deformation ◽  
Star Configuration ◽  
Deformation Approach

AbstractIn this work we construct an ultracompact star configuration in the framework of Gravitational Decoupling by the Minimal Geometric Deformation approach. We use the complexity factor as a complementary condition to close the system of differential equations. It is shown that for a polynomial complexity the resulting solution can be matched with two different modified-vacuum geometries.

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