Induced gravity and minimally and conformally coupled scalar fields in Bianchi-I cosmological models

Kamenshchik, Alexander Yu.; Pozdeeva, Ekaterina; Vernov, S. Yu.; Starobinsky, Alexei A.; Tronconi, Alessandro; Venturi, G.

doi:10.1103/physrevd.97.023536

Cited by 37 publications

(23 citation statements)

References 59 publications

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“…The same generic behavior near an anisotropic curvature singularity occurs for a non-minimally coupled scalar field in many cases, in particular, for a massive conformally coupled field, see the recent paper[41] in this connection.…”

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confidence: 54%

Anisotropic cosmological solutions in $$R + R^2$$ R + R 2 gravity

et al. 2018

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In this paper we investigate the past evolution of an anisotropic Bianchi I universe in R + R 2 gravity. Using the dynamical system approach we show that there exists a new two-parameter set of solutions that includes both an isotropic "false radiation" solution and an anisotropic generalized Kasner solution, which is stable. We derive the analytic behavior of the shear from a specific property of f (R) gravity and the analytic asymptotic form of the Ricci scalar when approaching the initial singularity. Finally, we numerically check our results.

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confidence: 54%

Anisotropic cosmological solutions in $$R + R^2$$ R + R 2 gravity

et al. 2018

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“…Let us consider the Bianchi I metric 15) where N, a k and also φ are functions of t. Injecting to (2.1), the Lagrangian is…”

Section: Bianchi I -Anisotropy Screeningmentioning

confidence: 99%

Anisotropy screening in Horndeski cosmologies

2020

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We consider anisotropic cosmologies in a particular shift-symmetric Horndeski theory containing the G µν ∂ µ φ∂ ν φ coupling, where G µν is the Einstein tensor. This theory admits stable in the future self-accelerating cosmologies whose tensor perturbations propagate with the velocity very close to the speed of light such that the theory agrees with the gravity wave observations. Surprisingly, we find that the anisotropies within the Bianchi I homogeneous spacetime model are screened at early time by the scalar charge, whereas at late times they are damped in the usual way, hence they are damped at all times. Therefore, contrary to what one would normally expect, the initial state of the universe close to the singularity cannot be anisotropic, although it seems it should be inhomogeneous. At the same time, we find that in the Bianchi IX case the universe can be strongly anisotropic close to the initial singularity even in the presence of a scalar charge.

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“…One can also use the same description of the hot or warm matter in other approaches to anisotropy, like the recent consideration of gravity with R 2 term [38] or with the sigmamodel like scalar field [39], or even in loop quantum gravity [40].…”

Section: Discussionmentioning

confidence: 99%

Cosmic anisotropy with reduced relativistic gas

Reis

Shapiro

2018

Eur. Phys. J. C

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The dynamics of cosmological anisotropies is investigated for Bianchi type I universe filled by a relativistic matter represented by the reduced relativistic gas model (RRG), with equation of state interpolating between radiation and matter. Previously it was shown that the interpolation is observed in the background cosmological solutions for homogeneous and isotropic universe and also for the linear cosmological perturbations. We extend the application of RRG to the Bianchi type I anisotropic model and find that the solutions evolve to the isotropic universe with the pressureless matter contents.

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Induced gravity and minimally and conformally coupled scalar fields in Bianchi-I cosmological models

Cited by 37 publications

References 59 publications

Anisotropic cosmological solutions in $$R + R^2$$ R + R 2 gravity

Anisotropic cosmological solutions in $$R + R^2$$ R + R 2 gravity

Anisotropy screening in Horndeski cosmologies

Cosmic anisotropy with reduced relativistic gas

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