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.

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.

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.

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.

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.

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.

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.

scholarly journals TRAVERSABLE WORMHOLES IN A STRING CLOUD

2008 ◽  
Vol 17 (08) ◽  
pp. 1179-1196 ◽  
Author(s):  
MARTÍN G. RICHARTE ◽  
CLAUDIO SIMEONE
Keyword(s):  
Thin Shell ◽  
Dimensional Space ◽  
Space Time ◽  
Exotic Matter ◽  
Spherically Symmetric ◽  
Related Model ◽  
Traversable Wormholes ◽  
Dimensional Space Time ◽  
Thin Shell Wormholes ◽  
The Stability

We study spherically symmetric thin shell wormholes in a string cloud background in (3 + 1)-dimensional space–time. The amount of exotic matter required for the construction, the traversability and the stability of such wormholes under radial perturbations are analyzed as functions of the parameters of the model. In addition, in the appendices a nonperturbative approach to the dynamics and a possible extension of the analysis to a related model are briefly discussed.

BOUNDS ON f(G) GRAVITY FROM ENERGY CONDITIONS

2010 ◽  
Vol 25 (27) ◽  
pp. 2325-2332 ◽  
Author(s):  
PUXUN WU ◽  
HONGWEI YU
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Energy Density ◽  
Modified Gravity ◽  
Energy Conditions ◽  
Model Parameters ◽  
Effective Energy ◽  
Raychaudhuri Equation ◽  
Accelerating Expansion

The f(G) gravity is a theory to modify the general relativity and it can explain the present cosmic accelerating expansion without the need of dark energy. In this paper the f(G) gravity is tested with the energy conditions. Using the Raychaudhuri equation along with the requirement that the gravity is attractive in the FRW background, we obtain the bounds on f(G) from the SEC and NEC. These bounds can also be found directly from the SEC and NEC within the general relativity context by the transformations: ρ → ρm + ρE and p → pm + pE, where ρE and pE are the effective energy density and pressure in the modified gravity. With these transformations, the constraints on f(G) from the WEC and DEC are obtained. Finally, we examine two concrete examples with WEC and obtain the allowed region of model parameters.

Self-gravitating anisotropic star using gravitational decoupling

2021 ◽  
Author(s):  
Baiju Dayanandan ◽  
T. T. Smitha ◽  
Sunil Maurya
Keyword(s):  
Compact Star ◽  
Radial Component ◽  
Energy Conditions ◽  
Regularity Conditions ◽  
Star Model ◽  
Anisotropic Solution ◽  
Seed System ◽  
The Stability ◽  
Metric Function ◽  
Anisotropic Star

Abstract This paper addresses a new gravitationally decoupled anisotropic solution for the compact star model via the minimal geometric deformation (MGD) approach. We consider a non-singular well-behaved gravitational potential corresponding to the radial component of the seed spacetime and embedding class I condition that determines the temporal metric function to solve the seed system completely. However, two different well-known mimic approaches such as pr = Θ1 1 and ρ = Θ0 0 have been employed to determine the deformation function which gives the solution of the second system corresponding to the extra source. In order to test the physical viability of the solution, we have checked several conditions such as regularity conditions, energy conditions, causality conditions, hydrostatic equilibrium, etc. Moreover, the stability of the solutions has been also discussed by the adiabatic index and its critical value. We find that the solutions set seems viable as far as observational data are concerned.

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.

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