scholarly journals Wormhole modeling supported by non-exotic matter

2019 ◽  
Vol 34 (28) ◽  
pp. 1950224 ◽  
Author(s):  
Gauranga C. Samanta ◽  
Nisha Godani
Keyword(s):  
Shape Function ◽  
Exotic Matter ◽  
Energy Conditions ◽  
Traversable Wormholes ◽  
Geometric Nature

In the present paper, the modeling of traversable wormholes, proposed by Morris and Thorne [Am. J. Phys. 56, 395 (1988)], is performed within the [Formula: see text] gravity with particular viable case [Formula: see text], where [Formula: see text], [Formula: see text] and [Formula: see text]. The energy conditions are analyzed using the shape function [Formula: see text] defined by Godani and Samanta [Int. J. Mod. Phys. D 28, 1950039 (2018)] and the geometric nature of wormholes is analyzed.

scholarly journals Wormhole modeling in R2 gravity with linear trace term

2020 ◽  
Vol 35 (08) ◽  
pp. 2050045
Author(s):  
Nisha Godani ◽  
Gauranga C. Samanta
Keyword(s):  
General Relativity ◽  
General Theory ◽  
Significant Contribution ◽  
Shape Function ◽  
Exotic Matter ◽  
Geometric Configuration ◽  
Energy Conditions ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Traversable Wormholes

Morris and Thorne1 proposed traversable wormholes, hypothetical connecting tools, using the concept of Einstein’s general theory of relativity. In this paper, the modification of general relativity (in particular [Formula: see text] theory of gravity defined by Harko et al.2) is considered, to study the traversable wormhole solutions. The function [Formula: see text] is considered as [Formula: see text], where [Formula: see text] and [Formula: see text] are controlling parameters. The shape and redshift functions appearing in the metric of wormhole structure have significant contribution in the development of wormhole solutions. We have considered both variable and constant redshift functions with a logarithmic shape function. The energy conditions are examined, geometric configuration is analyzed and the radius of the throat is determined in order to have wormhole solutions in absence of exotic matter.

Modeling of traversable wormholes in exponential f(R,T) gravity

2021 ◽  
Author(s):  
Chanchal Chawla ◽  
Archana Dixit ◽  
Anirudh Pradhan
Keyword(s):  
Shape Function ◽  
Anisotropy Parameter ◽  
Exotic Matter ◽  
Energy Conditions ◽  
Physical Parameters ◽  
Asymptotically Flat ◽  
Physical Constraints ◽  
Traversable Wormholes ◽  
Necessary Constraints ◽  
The Universe

In the present communication, we have studied the existence of wormholes described by a logarithmic shape function, in the exponential f(R, T) gravity given by f(R, T) = R + 2ξe^{ςt} where ξ and ς are arbitrary constants, under three different set of physical constraints. The logarithmic shape function is found to be well behaved satisfying all the necessary constraints for traversable and asymptotically flat wormholes. The obtained wormhole solutions are analyzed from the energy conditions for different values of involved physical constants. It has been observed that our proposed shape function for the exponential form of f(R, T) gravity, represents the existence of exotic matter with a standard violation of the NEC. Moreover, for the trace T=0 i.e. for the general relativity case with R being replaced by R+2, the wormhole geometry has been analyzed to prove the existence of exotic matter. Further, the behaviour of physical parameters such as the energy density ρ, the trace T, anisotropy parameter △ describing the geometry of the universe has been presented with the help of graphs.

Stable Morris Thorne wormholes supported by non-exotic matter

2021 ◽  
pp. 2150170
Author(s):  
Nisha Godani
Keyword(s):  
General Relativity ◽  
Gravity Model ◽  
Stability Condition ◽  
Modified Gravity ◽  
Shape Function ◽  
Exotic Matter ◽  
Energy Conditions ◽  
Traversable Wormholes ◽  
The Stability ◽  
Metric Function

The present work is focused on the study of traversable wormholes, proposed by Morris and Thorne [Wormholes in spacetime and their use for interstellar travel: A tool for teaching general relativity, Am. J. Phys. 56 (1988) 395], using the background of modified gravity. It is performed by using the models: I. [Formula: see text], II. [Formula: see text] and III. [Formula: see text], where [Formula: see text], [Formula: see text] and [Formula: see text] are constants. The Model I belongs to the theory of [Formula: see text] gravity, Model II belongs to the theory of [Formula: see text] gravity and Model III is a combination of Models I and II. These functions have been taken into account for the exploration of wormhole solutions. The shape function, a wormhole metric function, is newly defined which satisfies the flare out condition. Further, the stability condition and energy conditions, namely null, weak and dominant energy conditions, have been examined with respect to each model.

scholarly journals Traversable wormholes with exponential shape function in modified gravity and general relativity: A comparative study

2020 ◽  
Vol 29 (09) ◽  
pp. 2050068 ◽  
Author(s):  
Gauranga C. Samanta ◽  
Nisha Godani ◽  
Kazuharu Bamba
Keyword(s):  
General Relativity ◽  
Equation Of State ◽  
Comparative Study ◽  
Modified Gravity ◽  
Shape Function ◽  
Anisotropy Parameter ◽  
Energy Conditions ◽  
Traversable Wormholes

We have proposed a novel shape function on which the metric that models traversable wormholes is dependent. Using this shape function, the energy conditions, equation-of-state and anisotropy parameter are analyzed in [Formula: see text] gravity, [Formula: see text] gravity and general relativity. Furthermore, the consequences obtained with respect to these theories are compared. In addition, the existence of wormhole geometries is investigated.

Charging effect on traversable wormholes in f(R) = R + αRm + βR−n gravity

2021 ◽  
pp. 2150144
Author(s):  
Nisha Godani
Keyword(s):  
Shape Function ◽  
Energy Conditions ◽  
Logarithmic Form ◽  
Traversable Wormholes ◽  
Charging Effect

In this paper, traversable wormholes have been studied in [Formula: see text] gravity, where [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are constant. A simplest form of shape function and a logarithmic form of redshift function is considered to construct wormhole solutions. The range of parameters providing the wormhole solutions free from the matter violating the energy conditions is explored. Further, the effect of charge is analyzed on wormhole solutions.

Two different shape functions for wormholes in f(R) theory with non-commutative geometry and Lorentzian distribution

2020 ◽  
Vol 17 (11) ◽  
pp. 2050155
Author(s):  
Ambuj Kumar Mishra ◽  
Vipin Chandra Dubey ◽  
Umesh Kumar Sharma
Keyword(s):  
General Relativity ◽  
Shape Function ◽  
Anisotropy Parameter ◽  
Point Of View ◽  
Energy Conditions ◽  
Shape Functions ◽  
Throat Radius ◽  
Eos Parameter ◽  
Traversable Wormholes ◽  
Modified Formula

In this work, the solutions of traversable wormholes are investigated inside modified [Formula: see text] gravity under non-commutative geometry since matter possesses Lorentzian density distribution of a particle-like gravitation source. To find the exact wormhole solutions, two different shape functions [Formula: see text], [Formula: see text], and [Formula: see text], [Formula: see text], are considered. The first shape function was proposed by Mishra and Sharma [A new shape function for wormholes in [Formula: see text] gravity and General Relativity, preprint (2020), arXiv:2003.00298v1 [physics.gen-ph]], however the second is newly defined in this paper. The behaviors of both shape functions are analyzed with the throat radius [Formula: see text]. The equation-of-state (EoS) parameter energy conditions, and anisotropy parameter are discussed with graphical point of view.

scholarly journals Traversable wormholes and energy conditions with two different shape functions in f(R) gravity

2019 ◽  
Vol 28 (02) ◽  
pp. 1950039 ◽  
Author(s):  
Nisha Godani ◽  
Gauranga C. Samanta
Keyword(s):  
Energy Density ◽  
Shape Function ◽  
Energy Condition ◽  
State Parameter ◽  
Null Energy Condition ◽  
Energy Conditions ◽  
Radial Coordinate ◽  
Shape Functions ◽  
Anisotropic Parameter ◽  
Traversable Wormholes

Traversable wormholes, tunnel-like structures introduced by Morris and Thorne [Am. J. Phys. 56 (1988) 395], have a significant role in connection of two different spacetimes or two different parts of the same spacetime. The characteristics of these wormholes depend upon the redshift and shape functions which are defined in terms of radial coordinate. In literature, several shape functions are defined and wormholes are studied in [Formula: see text] gravity with respect to these shape functions [F. S. N. Lobo and M. A. Oliveira, Phys. Rev. D 80 (2009) 104012; H. Saiedi and B. N. Esfahani, Mod. Phys. Lett. A 26 (2011) 1211; S. Bahamonde, M. Jamil, P. Pavlovic and M. Sossich, Phys. Rev. D 94 (2016) 044041]. In this paper, two shape functions (i) [Formula: see text] and (ii) [Formula: see text], [Formula: see text], are considered. The first shape function is newly defined, however, the second one is collected from the literature [M. Cataldo, L. Liempi and P. Rodríguez, Eur. Phys. J. C 77 (2017) 748]. The wormholes are investigated for each type of shape function in [Formula: see text] gravity with [Formula: see text], where [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are real constants. Varying the parameter [Formula: see text] or [Formula: see text], [Formula: see text] model is studied in five subcases for each type of shape function. In each case, the energy density, radial and tangential pressures, energy conditions that include null energy condition, weak energy condition, strong energy condition and dominated energy condition and anisotropic parameter are computed. The energy density is found to be positive and all energy conditions are obtained to be violated which support the existence of wormholes. Also, the equation-of-state parameter is obtained to possess values less than [Formula: see text], that shows the presence of the phantom fluid and leads toward the expansion of the universe.

scholarly journals Generalised Ellis–Bronnikov wormholes embedded in warped braneworld background and energy conditions

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
Vivek Sharma ◽  
Suman Ghosh
Keyword(s):  
Extra Dimension ◽  
Shape Function ◽  
The Other ◽  
Exotic Matter ◽  
Energy Conditions ◽  
Warp Factor ◽  
Simple Modification ◽  
The Status ◽  
Warped Extra Dimension

AbstractEllis–Bronnikov (EB) wormholes require violation of null energy conditions at the ‘throat’. This problem was cured by a simple modification of the ‘shape function’, which introduces a new parameter $$m\ge 2$$ m ≥ 2 ($$m=2$$ m = 2 corresponds to the EB model). This leads to a generalised (GEB) version. In this work, we consider a model where the GEB wormhole geometry is embedded in a five dimensional warped background. We studied the status of all the energy conditions in detail for both EB and GEB embedding. We present our results analytically (wherever possible) and graphically. Remarkably, the presence of decaying warp factor leads to satisfaction of weak energy conditions even for the EB geometry, while the status of all the other energy conditions are improved compared to the four dimensional scenario. Besides inventing a new way to avoid the presence of exotic matter, in order to form a wormhole passage, our work reveals yet another advantage of having a warped extra dimension.

Wormhole models with exotic matter in Rastall gravity

2020 ◽  
Vol 17 (10) ◽  
pp. 2050146
Author(s):  
G. Mustafa ◽  
Tie-Cheng Xia
Keyword(s):  
Shape Function ◽  
Energy Condition ◽  
Null Energy Condition ◽  
Exotic Matter ◽  
Energy Conditions ◽  
Anisotropic Fluid ◽  
Shape Functions ◽  
Anisotropic Models ◽  
Specific Shape

In this paper, we examine the wormhole solutions by taking two different anisotropic models in Rastall gravity. For this purpose, we shall discuss anisotropic fluid to construct two different anisotropic models. Further, we shall employ two specific shape functions to calculate the behavior of energy conditions. The presence of exotic matter is confirmed in all the cases of this study due to the violation of the null energy condition. All the properties of shape function under both anisotropic models are fulfilled. It is noticed that wormhole solutions exist under the particular values of involved parameters in different cases in Rastall gravity.

Influence of modification of gravity on spherical wormhole models

2017 ◽  
Vol 32 (30) ◽  
pp. 1750163 ◽  
Author(s):  
Z. Yousaf ◽  
M. Ilyas ◽  
M. Z. Bhatti
Keyword(s):  
Equation Of State ◽  
Gravity Model ◽  
Modified Gravity ◽  
Shape Function ◽  
Exotic Matter ◽  
Energy Conditions ◽  
Barotropic Equation ◽  
The Stability

This paper explores some wormhole (WH) solutions in the background of additional matter contents of f(R, T) modified gravity. For this purpose, we have considered WH geometry filled with two physically different fluid configurations: one is anisotropic and another is anisotropic characterized by the barotropic equation of state. The energy conditions are examined with particular modified gravity model and found the existence of WH solutions even in the absence of exotic matter. Also, we have analyzed the behavior of shape function in this framework. The stability and physical existence of these solutions is studied with different fluid configurations. We conclude that in the absence of exotic matter, one can find WH solutions with particular model of modified gravity.

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