Exact and asymptotic solutions to tensor-scalar cosmologies

Oukouiss, A.

doi:10.1016/s0550-3213(96)00593-7

Cited by 6 publications

(3 citation statements)

References 18 publications

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“…Exact solutions with κ = 0 have been found to Eqs. ( 134) and (135) in [94,1004,108,942], and vacuum and radiation dominated solutions for arbitrary spatial curvature have been found in [95,899,111]. Some of the methods used in these papers are extended to anisotropic cosmologies in [898], and the asymptotics of FLRW cosmologies in scalar-tensor theories have been studied in [112,1125].…”

Section: General Scalar-tensor Theoriesmentioning

confidence: 99%

Modified Gravity and Cosmology

Clifton,

Ferreira,

Padilla

et al. 2011

Preprint

501

847

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In this review we present a thoroughly comprehensive survey of recent work on modified theories of gravity and their cosmological consequences. Amongst other things, we cover General Relativity, Scalar-Tensor, Einstein-Aether, and Bimetric theories, as well as TeVeS, f (R), general higher-order theories, Hořava-Lifschitz gravity, Galileons, Ghost Condensates, and models of extra dimensions including Kaluza-Klein, Randall-Sundrum, DGP, and higher co-dimension braneworlds. We also review attempts to construct a Parameterised Post-Friedmannian formalism, that can be used to constrain deviations from General Relativity in cosmology, and that is suitable for comparison with data on the largest scales. These subjects have been intensively studied over the past decade, largely motivated by rapid progress in the field of observational cosmology that now allows, for the first time, precision tests of fundamental physics on the scale of the observable Universe. The purpose of this review is to provide a reference tool for researchers and students in cosmology and gravitational physics, as well as a self-contained, comprehensive and up-to-date introduction to the subject as a whole.

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Section: General Scalar-tensor Theoriesmentioning

confidence: 99%

Modified Gravity and Cosmology

Clifton,

Ferreira,

Padilla

et al. 2011

Preprint

501

847

View full text Add to dashboard Cite

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“…In [44,45], some properties of the mentioned solutions have been discussed for large values of w . Furthermore, there are a few publications in which the solutions have been obtained in terms of the conformal time and other variables different from the scale factor and the BD scalar field [2,[46][47][48]…”

Section: Dust Cosmologiesmentioning

confidence: 99%

“…Moreover, a few classes of our solutions have no analog to those obtained by means of the corresponding conventional setting. We should note that the solutions herein can still be generalized by assuming ordinary matter in the bulk and/or supposing that the BD scalar field and the components of the metric are also functions of (further the cosmic time) the extra coordinate l. -In order to obtain the solutions herein, we have not introduced conformal time or other variables different from the scale factor and the BD scalar field; see, e.g., [2,[46][47][48]. -As our MBDT setting [1] has been formulated in arbitrary dimensions, it can be employed not only for obtaining the reduced solutions (for a specified model) in (3+1) dimensions but also it can be examined for deriving the solutions in (2+1) dimensions.…”

Section: Radiation Solutionsmentioning

confidence: 99%

Exact cosmological solutions in modified Brans–Dicke theory

Rasouli

Moniz

2016

Class. Quantum Grav.

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In this paper, we obtain exact cosmological vacuum solutions for an extended FLRW homogenous and isotropic Brans-Dicke (BD) universe in five dimensions for all values of the curvature index. Then, by employing the equations associated to a modified Brans-Dicke theory (MBDT) [1], we construct the physics on a four-dimensional hypersurface. We show that the induced matter obeys the equation of state of a fluid of a barotropic type. We discuss the properties of such an induced matter for some values of the equation of state parameter and analyze in detail their corresponding solutions. To illustrate the cosmological behaviors of the solutions, we contrast our solutions with those present the standard Brans-Dicke theory. We retrieve that, in MBDT scenario, it is impossible to find a physically acceptable solution associated to the negative curvature for both the dustdominated and radiation-dominated universes. However, for a spatially flat and closed universes, we argue that our obtained solutions are more general than those associated to the standard BD theory and, moreover, they contain a few classes of solutions which have no analog in the BD cosmology. For those particular cases, we further compare the results with those extracted in the context of the induced matter theory (IMT) and general relativity (GR). Furthermore, we discuss in detail the time behaviors of the cosmological quantities and compare them with recent observational data. We find a favorable range for the deceleration parameter associated to a matter-dominated spatially flat universe (for the late times) which is compatible with recent corresponding observational results.

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