Dynamic wormhole geometries in hybrid metric-Palatini gravity

Zangeneh, M. Kord

doi:10.1140/epjc/s10052-021-09059-y

Cited by 30 publications

(10 citation statements)

References 110 publications

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“…6 Numerical solution for Eq. (26) and Flaring-out condition validation/violation for varying α and ω (we assumed constant β for simplicity) in log-corrected gravity whereR is the Palatini scalar, constructed from Palatini curvature tensor, which reads [25]:…”

Section: Hybrid Metric-palatini Gravitymentioning

confidence: 99%

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On the existence and stability of traversable wormhole solutions in modified theories of gravity

Sokoliuk

Baransky

2021

Eur. Phys. J. C

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We study Morris–Thorne static traversable wormhole solutions in different modified theories of gravity. We focus our study on the quadratic gravity $$f({\mathscr {R}}) = {\mathscr {R}}+a{\mathscr {R}}^2$$ f ( R ) = R + a R 2 , power-law $$f({\mathscr {R}}) = f_0{\mathscr {R}}^n$$ f ( R ) = f 0 R n , log-corrected $$f({\mathscr {R}})={\mathscr {R}}+\alpha {\mathscr {R}}^2+\beta {\mathscr {R}}^2\ln \beta {\mathscr {R}}$$ f ( R ) = R + α R 2 + β R 2 ln β R theories, and finally on the exponential hybrid metric-Palatini gravity $$f(\mathscr {\hat{R}})=\zeta \bigg (1+e^{-\frac{\hat{{\mathscr {R}}}}{\varPhi }}\bigg )$$ f ( R ^ ) = ζ ( 1 + e - R ^ Φ ) . Wormhole fluid near the throat is adopted to be anisotropic, and redshift factor to have a constant value. We solve numerically the Einstein field equations and we derive the suitable shape function for each MOG of our consideration by applying the equation of state $$p_t=\omega \rho $$ p t = ω ρ . Furthermore, we investigate the null energy condition, the weak energy condition, and the strong energy condition with the suitable shape function b(r). The stability of Morris–Thorne traversable wormholes in different modified gravity theories is also analyzed in our paper with a modified Tolman–Oppenheimer–Voklov equation. Besides, we have derived general formulas for the extra force that is present in MTOV due to the non-conserved stress-energy tensor.

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Section: Hybrid Metric-palatini Gravitymentioning

confidence: 99%

“…where φ is scalar field and V (φ) is scalar potential (in metric-Palatini gravity scalar field in dynamic [35]). By varying the action, we could obtain following EFE form [19,25]:…”

Section: Hybrid Metric-palatini Gravitymentioning

confidence: 99%

On the existence and stability of traversable wormhole solutions in modified theories of gravity

Sokoliuk

Baransky

2021

Eur. Phys. J. C

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“…Apart from the Ricci scalar there are other invariants which have been introduced to modify the gravitational theory [37][38][39][40][41]. The Ricci scalar is constructed by the Levi-Civita connection, which is the fundamental geometric object of General Relativity.…”

Section: Introductionmentioning

confidence: 99%

Kantowski-Sachs cosmology in scalar-torsion theory

Paliathanasis¹

2023

Preprint

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In the context of scalar-torsion theory we investigate the evolution of the cosmological anisotropies for a Kantowski-Sachs background geometry. We study the phase-space of the gravitational field equations by determining the admitted stationary points and study their stability properties. For the potential function of the non-minimally coupled scalar field we assume the exponential and the power-law functions. Finally, we make use of Poincare variables in order to investigate the existence of stationary points at the infinity regime of the dynamics.

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“…In order to overcome the above impasse, some authors have developed many interesting wormhole models in another scenarios, such as higher dimensional theories like Einstein–Gauss–Bonnet, [ 34 ] warped extra dimensions, [ 35 ] GR extensions such as

f(R,T)

gravity, [ 36 ] scale–dependent, [ 37 ] asymptotically safety gravity, [ 38 ] conformal Weyl gravity, [ 39,40 ] teleparalell gravity, [ 41 ] kinetic gravity, [ 42 ] hybrid Palatini–metric gravity, [ 43 ] action dependent Lagrangian theories [ 44 ] and by incorporating 3–form fields [ 45 ] and pole dark energy, [ 46 ] to name a few. In all the mentioned works, the non violation of energy conditions and the satisfaction of the flare–out condition are achieved and justified by extra dimensions and new terms modifying the usual Einstein theory of gravity, GR.…”

Section: Introductionmentioning

confidence: 99%

Minimally Deformed Wormholes Inspired by Noncommutative Geometry

Tello‐Ortiz

Mishra

Alvarez

et al. 2022

Fortschritte der Physik

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In this article, new wormhole solutions in the framework of General Relativity are presented. Taking advantage of gravitational decoupling by means of minimal geometric deformation approach and, the so–called noncommutative geometry Gaussian and Lorentzian density profiles, the seminal Morris–Thorne space–time is minimally deformed providing new asymptotically wormhole solutions. Constraining the signature of some parameters, the dimensionless constant α is bounded using the flare–out and energy conditions. In both cases, this results in an energy–momentum tensor that violates energy conditions, thus the space–time is threading by an exotic matter distribution. However, it is possible to obtain a positive defined density at the wormhole throat and its neighborhood. To further support the study a thoroughly graphical analysis has been performed.

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Dynamic wormhole geometries in hybrid metric-Palatini gravity

Cited by 30 publications

References 110 publications

On the existence and stability of traversable wormhole solutions in modified theories of gravity

On the existence and stability of traversable wormhole solutions in modified theories of gravity

Kantowski-Sachs cosmology in scalar-torsion theory

Minimally Deformed Wormholes Inspired by Noncommutative Geometry

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