scholarly journals Some specific wormhole solutions in f(R)-modified gravity theory

2021 ◽  
pp. 2150024
Author(s):  
Bikram Ghosh ◽  
Saugata Mitra ◽  
Subenoy Chakraborty
Keyword(s):  
Modified Gravity ◽  
Shape Function ◽  
Matter Field ◽  
Gravity Theory ◽  
Energy Conditions ◽  
Spherically Symmetric ◽  
Shape Functions ◽  
Matter Distribution ◽  
Anisotropic Matter ◽  
Modified Gravity Theory

The paper deals with the static spherically symmetric wormhole solutions in [Formula: see text]-modified gravity theory with anisotropic matter field and for some particular choices for the shape functions. This work may be considered as an extension of the general formalism in [S. Halder, S. Bhattacharya and S. Chakraborty, Phys. Lett. B 791, 270 (2019)] for finding wormhole solutions. For isotropic matter distribution it has been shown that wormhole solutions are possible for zero tidal force and it modifies the claim in [M. Cataldo, L. Leimpi and P. Rodriguez, Phys. Lett. B 757, 130 (2016)]. Finally, energy conditions are examined and it is found that all energy conditions are satisfied in a particular domain with a particular choice of the shape function.

Spherically symmetric static wormhole models in the Einsteinian cubic gravity

2020 ◽  
Vol 17 (14) ◽  
pp. 2050214
Author(s):  
G. Mustafa ◽  
Tie-Cheng Xia ◽  
Ibrar Hussain ◽  
M. Farasat Shamir
Keyword(s):  
Shape Function ◽  
Necessary Conditions ◽  
General Relation ◽  
Energy Conditions ◽  
Spherically Symmetric ◽  
Shape Functions ◽  
Anisotropic Matter ◽  
Lorentzian Signature ◽  
Fields Equations

Our aim is to discuss spherically symmetric static wormholes with the Lorentzian signature in the Einsteinian cubic gravity for two different models of pressure sources. First, we calculate the modified fields equations for the Einsteinian cubic gravity for the wormhole geometry under the anisotropic matter. Then we investigate the shape-function for two different models, which can be taken as a part of the general relation, namely, [Formula: see text]. We further study the energy conditions for both the models in the background of the Einsteinian cubic gravity. We show that our obtained shape-functions satisfy all the necessary conditions for the existence of wormhole solutions in the Einsteinian cubic gravity for some particular values of the different involved parameters. We also discuss the behavior of the energy conditions especially the null and the weak energy conditions for the wormhole models in the Einsteinian cubic gravity.

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.

scholarly journals Stable Wormholes in the Background of an Exponential f(R) Gravity

Universe ◽  
2020 ◽  
Vol 6 (4) ◽  
pp. 48 ◽  
Author(s):  
Ghulam Mustafa ◽  
Ibrar Hussain ◽  
M. Farasat Shamir
Keyword(s):  
Stability Analysis ◽  
Equation Of State ◽  
Shape Function ◽  
Energy Condition ◽  
Energy Conditions ◽  
Anisotropic Fluid ◽  
Spherically Symmetric ◽  
Shape Functions ◽  
Spacetime Geometry ◽  
Specific Shape

The current paper is devoted to investigating wormhole solutions with an exponential gravity model in the background of f ( R ) theory. Spherically symmetric static spacetime geometry is chosen to explore wormhole solutions with anisotropic fluid source. The behavior of the traceless matter is studied by employing a particular equation of state to describe the important properties of the shape-function of the wormhole geometry. Furthermore, the energy conditions and stability analysis are done for two specific shape-functions. It is seen that the energy condition are to be violated for both of the shape-functions chosen here. It is concluded that our results are stable and realistic.

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.

Wormhole solutions in modified f(R,φ,X) gravity

2021 ◽  
Vol 36 (04) ◽  
pp. 2150021
Author(s):  
M. Farasat Shamir ◽  
Adnan Malik ◽  
G. Mustafa
Keyword(s):  
Shape Function ◽  
Scalar Potential ◽  
Three Dimensional ◽  
State Parameter ◽  
Energy Conditions ◽  
Kinetic Term ◽  
Anisotropic Fluid ◽  
Shape Functions ◽  
Current Analysis ◽  
Static Space

This work aims to investigate the wormhole solutions in the background of [Formula: see text] theory of gravity, where [Formula: see text] is Ricci scalar, [Formula: see text] is scalar potential, and [Formula: see text] is the kinetic term. We consider spherically symmetric static space–time for exploring the wormhole geometry with anisotropic fluid. For our current analysis, we consider a particular equation of state parameter to study the behavior of traceless fluid and examine the physical behavior of energy density and pressure components. Furthermore, we also choose a particular shape function and explore the energy conditions. It can be noticed that energy conditions are violated for both shape functions. The violation of energy conditions indicates the existence of exotic matter and wormhole. Therefore, it can be concluded that our results are stable and realistic. The interesting feature of this work is to show two- and three-dimensional plotting for the analysis of wormhole geometry.

scholarly journals A Modified Gravity Theory: Null Aether

2019 ◽  
Vol 71 (3) ◽  
pp. 312 ◽  
Author(s):  
Metin Gürses ◽  
Çetin Şentürk
Keyword(s):  
Modified Gravity ◽  
Gravity Theory ◽  
Modified Gravity Theory

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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