Hybrid Metric-Palatini Gravity: Black Holes, Wormholes, Singularities, and Instabilities

Бронников, К. А.; Bolokhov, S. V.; Skvortsova, M. V.

doi:10.1134/s0202289320030044

Cited by 23 publications

(25 citation statements)

References 48 publications

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“…In this respect, we can note that HMPG, being a purely geometric source of scalar fields, both canonical and phantom, can provide a natural framework for wormhole construction without other "exotic" sources. Within spherical symmetry, this has already been confirmed [14,15], and a similar consideration in cylindrical symmetry can be one of the subjects of our further studies.…”

supporting

confidence: 74%

“…It is of interest that HMPG can be obtained from Palatini R 2 gravity with a Higgs scalar field under the requirement of Weyl invariance [12]. Some papers have been devoted to the possible existence and properties of vacuum static, spherically symmetric black holes and wormholes in HMPD [13][14][15], as well as static cylindrically symmetric configurations that are intended to reproduce the basic properties of cosmic strings [16].…”

Section: Introductionmentioning

confidence: 99%

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Hybrid Metric-Palatini Gravity: Regular Stringlike Configurations

2020

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We discuss static, cylindrically symmetric vacuum solutions of hybrid metric-Palatini gravity (HMPG), a recently proposed theory that has been shown to successfully pass the local observational tests and produce a certain progress in cosmology. We use HMPG in its well-known scalar-tensor representation. The latter coincides with general relativity containing, as a source of gravity, a conformally coupled scalar field ϕ and a self-interaction potential V(ϕ). The ϕ field can be canonical or phantom, and, accordingly, the theory splits into canonical and phantom sectors. We seek solitonic (stringlike) vacuum solutions of HMPG, that is, completely regular solutions with Minkowski metric far from the symmetry axis, with a possible angular deficit. A transition of the theory to the Einstein conformal frame is used as a tool, and many of the results apply to the general Bergmann-Wagoner-Nordtvedt class of scalar-tensor theories as well as f(R) theories of gravity. One of these results is a one-to-one correspondence between stringlike solutions in the Einstein and Jordan frames if the conformal factor that connects them is everywhere regular. An algorithm for the construction of stringlike solutions in HMPG and scalar-tensor theories is suggested, and some examples of such solutions are obtained and discussed.

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supporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Hybrid Metric-Palatini Gravity: Regular Stringlike Configurations

2020

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“…α μν is the Levi-Civita connection for metric which is conformal to our wormhole background metric (h μν = φg μν ) [3]. We could also rewrite Eq.…”

Section: Hybrid Metric-palatini Gravitymentioning

confidence: 99%

“…5.2 f (R) = f 0 R n gravity MTOV extra force for power law gravity have following form: (3) As usual, we depicted the solution for Eq. (47) on the Fig.…”

Section: F (R) = R + αR 2 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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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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“…It is interesting to note that this theory, which in the linear approach takes the form R + f (R), one retains the positive results through the Einstein-Hilbert term R and the addi-tional gravitational corrections are given by the metric-affine f (R) component, where the Palatini curvature scalar R is constructed in terms of an independent connection. A wide variety of applications of this hybrid metric-Palatini theory has been explored, namely, in considering that dark matter is a geometric effect of modified gravity [25,26], in exploring the Cauchy problem [27] and the Noether symmetries [28], black hole, wormhole and stellar solutions [29][30][31][32][33][34], the Einstein static Universe [35], string-like configurations [36,37], and thick branes [38], among others [39].…”

Section: Introductionmentioning

confidence: 99%

Thick brane structures in generalized hybrid metric-Palatini gravity

2021

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In this work, we study 5-dimensional braneworld scenarios in the scalar-tensor representation of the generalized hybrid metric-Palatini gravitational theory. We start by considering a model for a brane supported purely by the gravitational scalar fields of the theory and then consider other distinct cases where the models are also supported by an additional matter scalar field. We investigate the stability of the gravity sector and show that the models are all robust against small fluctuations of the metric. In particular, in the presence of the additional scalar field, we find that the profile of the gravitational zero mode may be controlled by the parameters of the model, being also capable of developing internal structure.

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Hybrid Metric-Palatini Gravity: Black Holes, Wormholes, Singularities, and Instabilities

Cited by 23 publications

References 48 publications

Hybrid Metric-Palatini Gravity: Regular Stringlike Configurations

Hybrid Metric-Palatini Gravity: Regular Stringlike Configurations

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

Thick brane structures in generalized hybrid metric-Palatini gravity

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