Noncommutative wormhole solutions in F(T, T𝒢) gravity

2017 ◽  
Vol 32 (13) ◽  
pp. 1750083 ◽  
Author(s):  
M. Sharif ◽  
Kanwal Nazir
Keyword(s):  
Noncommutative Geometry ◽  
Energy Conditions ◽  
Spherically Symmetric ◽  
Wormhole Solution

This paper is devoted to the study of static spherically symmetric wormhole solutions along with noncommutative geometry in the background of F(T, T[Formula: see text]) gravity. We assume a nonzero redshift function as well as two well-known models of this gravity and discuss the behavior of null/weak energy conditions graphically. We conclude that there does not exist any physically acceptable wormhole solution for the first model, but there is a chance to develop physically acceptable wormhole solution in a particular region for the second model.

scholarly journals Noncommutative Wormhole Solutions in Einstein Gauss-Bonnet Gravity

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Shamaila Rani ◽  
Abdul Jawad
Keyword(s):  
Noncommutative Geometry ◽  
Equilibrium Condition ◽  
Shape Function ◽  
Energy Conditions ◽  
Spherically Symmetric ◽  
Bonnet Gravity

We explore static spherically symmetric wormhole solutions in the framework ofn-dimensional Einstein Gauss-Bonnet gravity. Our objective is to find out wormhole solutions that satisfy energy conditions. For this purpose, we consider two frameworks such as Gaussian distributed and Lorentzian distributed noncommutative geometry. Taking into account constant redshift function, we obtain solutions in the form of shape function. The fifth and sixth dimensional solutions with positive as well as negative Gauss-Bonnet coefficient are discussed. Also, we check the equilibrium condition for the wormhole solutions with the help of generalized Tolman-Oppenheimer-Volkoff equation. It is interesting to mention here that we obtain fifth dimensional stable wormhole solutions in both distributions that satisfy the energy conditions.

scholarly journals Wormholes in 4D Einstein–Gauss–Bonnet gravity

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Kimet Jusufi ◽  
Ayan Banerjee ◽  
Sushant G. Ghosh
Keyword(s):  
Symmetric Solution ◽  
Shape Function ◽  
Energy Conditions ◽  
Spherically Symmetric ◽  
Coupling Constant ◽  
Volume Integral ◽  
Wormhole Solution ◽  
Anisotropic Matter ◽  
Spherically Symmetric Solution ◽  
Significant Interest

Abstract Recent times witnessed a significant interest in regularizing, a $$ D \rightarrow 4 $$D→4 limit, of EGB gravity initiated by Glavan and Lin [Phys. Rev. Lett. 124, 081301 (2020)] by re-scaling GB coupling constant as $$\alpha /(D-4)$$α/(D-4) and taking limit $$D \rightarrow 4$$D→4, and in turn these regularized 4D gravities have nontrivial gravitational dynamics. Interestingly, the maximally or spherically symmetric solution to all the regularized gravities coincides in the 4D case. In view of this, we obtain an exact spherically symmetric wormhole solution in the 4D EGB gravity for an isotropic and anisotropic matter sources. In this regard, we consider also a wormhole with a specific radial-dependent shape function, a power-law density profile as well as by imposing a particular equation of state. To this end, we analyze the flare-out conditions, embedding diagrams, energy conditions and the volume integral quantifier. In particular our −ve branch results, in the limit $$\alpha \rightarrow 0$$α→0, reduced exactly to vis-$$\grave{a}$$a`-vis 4D Morris-Thorne of GR.

Study of galactic halo F(T,TG) wormhole solutions

2017 ◽  
Vol 27 (01) ◽  
pp. 1750170
Author(s):  
M. Sharif ◽  
Kanwal Nazir
Keyword(s):  
Equilibrium Condition ◽  
Galactic Halo ◽  
Shape Function ◽  
Energy Conditions ◽  
Spherically Symmetric ◽  
Wormhole Solution ◽  
Torsion Scalar ◽  
Specific Formula ◽  
Bonnet Term

In this paper, we investigate static spherically symmetric wormhole solutions with galactic halo region in the background of [Formula: see text] gravity. Here, [Formula: see text] represents torsion scalar and [Formula: see text] is teleparallel equivalent Gauss–Bonnet term. For this purpose, we consider a diagonal tetrad and two specific [Formula: see text] models. We analyze the wormhole structure through shape function graphically for both models. We also investigate the behavior of null/weak energy conditions. Finally, we evaluate the equilibrium condition to check stability of the wormhole solutions. It is concluded that there exists physically viable wormhole solution only for the first model that turns out to be stable.

scholarly journals Collapsing Wormholes Sustained by Dustlike Matter

Universe ◽  
2020 ◽  
Vol 6 (10) ◽  
pp. 186
Author(s):  
Pavel E. Kashargin ◽  
Sergey V. Sushkov
Keyword(s):  
General Relativity ◽  
General Solution ◽  
Space Time ◽  
Time Structure ◽  
Energy Conditions ◽  
Spherically Symmetric ◽  
Friedmann Universe ◽  
Dust Shell ◽  
Wormhole Solution ◽  
Space Time Structure

It is well known that static wormhole configurations in general relativity (GR) are possible only if matter threading the wormhole throat is “exotic”—i.e., violates a number of energy conditions. For this reason, it is impossible to construct static wormholes supported only by dust-like matter which satisfies all usual energy conditions. However, this is not the case for non-static configurations. In 1934, Tolman found a general solution describing the evolution of a spherical dust shell in GR. In this particular case, Tolman’s solution describes the collapsing dust ball; the inner space-time structure of the ball corresponds to the Friedmann universe filled by a dust. In the present work we use the general Tolman’s solution in order to construct a dynamic spherically symmetric wormhole solution in GR with dust-like matter. The solution constructed represents the collapsing dust ball with the inner wormhole space-time structure. It is worth noting that, with the dust-like matter, the ball is made of satisfies the usual energy conditions and cannot prevent the collapse. We discuss in detail the properties of the collapsing dust wormhole.

Noncommutative wormhole solutions in f(G) gravity

2015 ◽  
Vol 30 (28) ◽  
pp. 1550142 ◽  
Author(s):  
M. Sharif ◽  
H. Ismat Fatima
Keyword(s):  
Shape Function ◽  
Energy Conditions ◽  
Radial Coordinate ◽  
Spherically Symmetric ◽  
Wormhole Solution ◽  
Physical Solution ◽  
Bonnet Gravity ◽  
First Case ◽  
Normal Matter ◽  
Text Model

In this paper, we study noncommutative static spherically symmetric wormhole solutions in the context of modified Gauss–Bonnet gravity. We explore these solutions either by assuming a viable [Formula: see text] model to construct shape function or by specifying the shape function to deduce [Formula: see text] model. The energy conditions are discussed for both types of wormholes. In the first case, we find a physically acceptable wormhole solution threaded by normal matter for all values of radial coordinate [Formula: see text] while the second case gives physical solution only for large values of [Formula: see text].

Study of gravitational decoupled anisotropic solution

2019 ◽  
Vol 28 (16) ◽  
pp. 2040004
Author(s):  
M. Sharif ◽  
Sobia Sadiq
Keyword(s):  
Energy Momentum Tensor ◽  
Momentum Tensor ◽  
Energy Conditions ◽  
Spherically Symmetric ◽  
Anisotropic Model ◽  
Field Equations ◽  
Anisotropic Solution ◽  
Spherically Symmetric Solution ◽  
Gravitational Source ◽  
The Stability

This paper formulates the exact static anisotropic spherically symmetric solution of the field equations through gravitational decoupling. To accomplish this work, we add a new gravitational source in the energy–momentum tensor of a perfect fluid. The corresponding field equations, hydrostatic equilibrium equation as well as matching conditions are evaluated. We obtain the anisotropic model by extending the known Durgapal and Gehlot isotropic solution and examined the physical viability as well as the stability of the developed model. It is found that the system exhibits viable behavior for all fluid variables as well as energy conditions and the stability criterion is fulfilled.

The “Planckonions”

2019 ◽  
Vol 34 (33) ◽  
pp. 1950268
Author(s):  
Mofazzal Azam ◽  
Farook Rahaman ◽  
M. Sami ◽  
Jitesh R. Bhatt
Keyword(s):  
Mass Formula ◽  
Energy Conditions ◽  
Generalized Function ◽  
Spherically Symmetric ◽  
Planck Length ◽  
Spherical Shells ◽  
Central Singularity ◽  
Time Component ◽  
Stellar Configuration ◽  
Central Sphere

We consider a spherically symmetric stellar configuration with a density profile [Formula: see text]. This configuration satisfies the Schwarzchild black hole condition [Formula: see text] for every [Formula: see text]. We refer to it as “Planckonion”. The interesting thing about the Planckonion is that it has an onion-like structure. The central sphere with radius of the Planck-length [Formula: see text] has one unit of the Planck-mass [Formula: see text]. Subsequent spherical shells of radial width [Formula: see text] contain exactly one unit of [Formula: see text]. We study this stellar configuration using Tolman–Oppenheimer–Volkoff equation and show that the equation is satisfied if pressure [Formula: see text]. On the geometrical side, the space component of the metric blows up at every point. The time component of the metric is zero inside the star but only in the sense of a distribution (generalized function). The Planckonions mimic some features of black holes but avoid appearance of central singularity because of the violation of null energy conditions.

Study of some compact objects in R + 2βT gravity

2019 ◽  
Vol 28 (16) ◽  
pp. 2040005
Author(s):  
Arfa Waseem ◽  
M. Sharif
Keyword(s):  
Stellar System ◽  
Graphical Analysis ◽  
Compact Objects ◽  
Stellar Structure ◽  
Energy Conditions ◽  
Spherically Symmetric ◽  
Field Equations ◽  
Star Models ◽  
Mit Bag Model ◽  
Text Model

The aim of this work is to examine the nature as well as physical characteristics of anisotropic spherically symmetric stellar candidates in the context of [Formula: see text] gravity. We assume that the fluid components such as pressure and energy density are related through MIT bag model equation-of-state in the interior of stellar system. In order to analyze the structure formation of some specific star models, the field equations are constructed using Krori–Barua solution in which the unknown constants are evaluated by employing observed values of radii and masses of the considered stars. We check the consistency of [Formula: see text] model through the graphical analysis of energy conditions as well as stability of stellar structure. It is found that our considered stars show viable as well as stable behavior for this model.

Study of conformally flat polytropes with tilted congruence

2018 ◽  
Vol 27 (07) ◽  
pp. 1850063 ◽  
Author(s):  
M. Sharif ◽  
Sobia Sadiq
Keyword(s):  
Equation Of State ◽  
Matter Content ◽  
Energy Conditions ◽  
Spherically Symmetric ◽  
Conformally Flat ◽  
Flat Condition ◽  
Polytropic Equation ◽  
Dissipative Fluid ◽  
Symmetric Spacetime ◽  
Fluid Configuration

This paper is aimed to study the modeling of spherically symmetric spacetime in the presence of anisotropic dissipative fluid configuration. This is accomplished for an observer moving relative to matter content using two cases of polytropic equation-of-state under conformally flat condition. We formulate the corresponding generalized Tolman–Oppenheimer–Volkoff equation, mass equation, as well as energy conditions for both cases. The conformally flat condition is imposed to find an expression for anisotropy which helps to study spherically symmetric polytropes. Finally, Tolman mass is used to analyze stability of the resulting models.

Study of tilted anisotropic polytropes

2019 ◽  
Vol 28 (03) ◽  
pp. 1950051
Author(s):  
M. Sharif ◽  
Sobia Sadiq
Keyword(s):  
Equations Of State ◽  
Conservation Equation ◽  
Specific Form ◽  
Energy Conditions ◽  
Spherically Symmetric ◽  
Conformally Flat ◽  
Anisotropic Matter ◽  
Conformal Flatness ◽  
Energy Bound ◽  
Aids Study

The purpose of this paper is to construct spherically symmetric models for anisotropic matter configurations by imposing conformally flat conditions. This work is done for a relatively moving observer with matter using two types of polytropic equations of state. We evaluate the corresponding conservation equation, mass equation as well as energy constraints for both choices of equations of state. The conformal flatness is employed to find a specific form of anisotropy which aids study to spherical polytropic configurations. It is found that the first model satisfies all the energy conditions while the second model does not meet the dominant energy bound. It is also found that both models remain stable throughout the evolution.

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