Wormhole geometries in fourth-order conformal Weyl gravity

Varieschi, Gabriele U.; Ault, Kellie L.

doi:10.1142/s0218271816500644

Cited by 28 publications

(15 citation statements)

References 60 publications

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“…Hermann Weyl [30,31] introduced conformal gravity or Weyl gravity, for cosmology conformal gravity is also of concern. Tanhayi et al [32] shown that the estimated value of cosmological constant and Hubble parameter are close to their measured values. They studied the dependence of Hubble parameter and cosmological constant in Weyl gravity, as a function of t and r. Ghanaatian et al [33] considered the modified gravity coupled by Weyl tensor in spatially flat Friedmann-Lemaître-Robertson-Walker (FLRW) metric, they described the cosmic expansion of the universe also they checked stability conditions of models.…”

Section: Introductionmentioning

confidence: 68%

Cosmological and thermodynamics analysis in Weyl gravity

2020

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In the framework of modified Weyl gravity, we observe the equilibrium picture of the thermodynamical laws for flat Friedmann-Robertson-Walker metric with chameleon scalar field and analyze the validity of the generalized second law of thermodynamics and thermal equilibrium condition for Hubble horizon along with Bekenstien-Hawking entropy. Also, we examine the effective equation of state parameter as well as the square speed of sound. By assuming four different choices of deceleration parameter, we investigate the behavior of equation of state parameter as well as the square speed of sound. The validity of generalized second law of thermodynamics and thermal equilibrium condition is also checked by taking the observational values of the model parameters from CC+H o dataset.

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Section: Introductionmentioning

confidence: 68%

Cosmological and thermodynamics analysis in Weyl gravity

2020

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“…The sphere at r = r 0 is mapped to the throat of the wormhole. The relation 16) implies, that the transformation (2.12) can be equivalently characterised in terms of r ± . According to (2.13) r can become infinite or even negative for |η 0 | < π/2.…”

Section: Domain Of the Transformationmentioning

confidence: 99%

Wormholes in conformal gravity

Hohmann

Pfeifer

Raidal

et al. 2018

J. Cosmol. Astropart. Phys.

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We present a new class of solutions for static spherically symmetric wormhole spacetimes in conformal gravity and outline a detailed method for their construction. As an explicit example, we construct a class of traversable and non-traversable wormholes that are locally conformal to Schwarzschild-(anti) de Sitter spacetimes. These wormhole spacetimes are exact vacuum solutions in, but not being limited to, Weyl gravity and conformal scalar-tensor theories. Importantly, the method implies that every conformal theory of gravity with static spherically symmetric solutions will trivially contain wormholes without the need for exotic matter. Applying those results on gravitational theories that possess conformal symmetry in the ultraviolet regime, the central singularities of black holes can be replaced with wormhole throats. We speculate on possible phenomenological consequences. We also discuss the inclusion of matter fields and give explicit examples of charged wormholes in Weyl gravity and conformal scalar-tensor gravity.

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“…In fact, in the context of f (R) theories of gravity, the solution of wormholes have attracted much attention where wormholes can be theoretically constructed with the presence of normal matter [26,27]. This type of solutions were also found in f (T ) gravity [28,29], hybrid metric-Palatini theory [30], multimetric gravity [31], Rastall gravity [32], conformal Weyl gravity [33,34], modified gravity [35], Horndeski theory of gravity [36] and other theories.…”

Section: Introductionmentioning

confidence: 97%

Wormhole geometries in f(Q) gravity and the energy conditions

et al. 2021

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Following the recent theory of f(Q) gravity, we continue to investigate the possible existence of wormhole geometries, where Q is the non-metricity scalar. Recently, the non-metricity scalar and the corresponding field equations have been studied for some spherically symmetric configurations in Mustafa (Phys Lett B 821:136612, 2021) and Lin and Zhai (Phys Rev D 103:124001, 2021). One can note that field equations are different in these two studies. Following Lin and Zhai (2021), we systematically study the field equations for wormhole solutions and found the violation of null energy conditions in the throat neighborhood. More specifically, considering specific choices for the f(Q) form and for constant redshift with different shape functions, we present a class of solutions for static and spherically symmetric wormholes. Our survey indicates that wormhole solutions could not exist for specific form function $$f(Q)= Q+ \alpha Q^2$$ f ( Q ) = Q + α Q 2 . To summarize, exact wormhole models can be constructed with violation of the null energy condition throughout the spacetime while being $$\rho \ge 0$$ ρ ≥ 0 and vice versa.

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Wormhole geometries in fourth-order conformal Weyl gravity

Cited by 28 publications

References 60 publications

Cosmological and thermodynamics analysis in Weyl gravity

Cosmological and thermodynamics analysis in Weyl gravity

Wormholes in conformal gravity

Wormhole geometries in f(Q) gravity and the energy conditions

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