Scalar–tensor theories of gravity: validity of the cosmic no-hair conjecture

This paper deals with the cosmic no-hair conjecture for anisotropic Bianchi models in the scalar–tensor theory of gravity. Herein, we have considered both the Jordan frame and the Einstein frame to describe the scalar–tensor theory of gravity and examine the conjecture. In the Jordan frame, one should restrict both the coupling function of the scalar field and the coupling parameter, in addition to the usual energy conditions for the matter field, to maintain the validity of the cosmic no-hair conjecture, while in the Einstein frame, the restrictions are purely on the energy conditions.

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Is Spacetime Non-metric?

Expert Opinion on Astronomy and Astrophysics ◽

10.18063/eoaa.v2i1.384 ◽

2018 ◽

Vol 2 (1) ◽

Cited By ~ 2

Author(s):

Mark D. Roberts

Keyword(s):

General Relativity ◽

Higher Dimensions ◽

Christoffel Symbol ◽

Einstein Frame ◽

Jordan Frame ◽

Scalar Tensor Theory ◽

Field Equations ◽

Extra Information ◽

Tensor Theory ◽

Palatini Variation

If one assumes higher dimensions and that dimensional reduction from higher dimensions produces scalar-tensor theory and also that Palatini variation is the correct method of varying scalar-tensor theory then spacetime is nonmetric. Palatini variation of Jordan frame lagrangians gives an equation relating the dilaton to the object of non-metricity and hence the existence of the dilaton implies that the spacetime connection is more general than that given soley by the Christoffel symbol of general relativity. Transferring from Jordan to Einstein frame, which connection, lagrangian, field equations and stress conservation equations occur are discussed: it is found that the Jordan frame has more information, this can be expressed in several ways, the simplest is that the extra information corresponds to the function multiplying the Ricci scalar in the action. The Einstein frame has the advantages that stress conservation implies no currents and that the field equations are easier to work with. This is illustrated by application to Robertson-Walker spacetime.

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Superdense Stellar Configurations in the Bimetric Scalar-Tensor Theory of Gravity

Communications of the Byurakan Astrophysical Observatory ◽

10.52526/25792776-2018.2.2-327 ◽

2018 ◽

pp. 327-337

Author(s):

L. Sh. Grigorian ◽

H. F. Khachatryan ◽

A. A. Saharian

Keyword(s):

General Relativity ◽

Scalar Field ◽

Neutron Stars ◽

White Dwarfs ◽

Coupling Parameter ◽

Spherically Symmetric ◽

Scalar Tensor Theory ◽

Metric Tensor ◽

Tensor Theory ◽

Theory Of Gravity

Models of static spherically-symmetric stellar configurations are discussed within the framework of the Bimetric scalar-tensor theory of gravity. The latter, in addition to the metric tensor and the scalar field, contains a background metric tensor as an absolute variable of the theory. The simplest variant of the theory with a constant coupling parameter and with a zero cosmological function is considered. The analysis includes both the white dwarfs and neutron stars. It is shown that, depending on the value of the theory parameter, the corresponding masses can be notably larger than those in general relativity.

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Inflation with Scalar-Tensor Theory of Gravity

Symmetry ◽

10.3390/sym12081267 ◽

2020 ◽

Vol 12 (8) ◽

pp. 1267

Author(s):

Dalia Saha ◽

Susmita Sanyal ◽

Abhik Kumar Sanyal

Keyword(s):

Present Article ◽

Power Law ◽

Coupling Parameter ◽

Scalar Tensor Theory ◽

Tensor Theory ◽

Theory Of Gravity ◽

Inflationary Parameters

The latest released data from Planck in 2018 put up tighter constraints on inflationary parameters. In the present article, the in-built symmetry of the non-minimally coupled scalar-tensor theory of gravity is used to fix the coupling parameter, the functional Brans–Dicke parameter, and the potential of the theory. It is found that all the three different power-law potentials and one exponential pass these constraints comfortably, and also gracefully exit from inflation.

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BRANS–DICKE THEORY: JORDAN VERSUS EINSTEIN FRAME

Modern Physics Letters A ◽

10.1142/s021773230702261x ◽

2007 ◽

Vol 22 (05) ◽

pp. 367-375 ◽

Cited By ~ 31

Author(s):

A. BHADRA ◽

K. SARKAR ◽

D. P. DATTA ◽

K. K. NANDI

Keyword(s):

General Relativity ◽

Second Order ◽

Einstein Frame ◽

Jordan Frame ◽

Scalar Tensor Theory ◽

Order Accuracy ◽

Deflection Of Light ◽

Tensor Theory ◽

Gravitational Deflection Of Light ◽

Gravitational Deflection

It is well known that, in contrast to general relativity, there are two conformally related frames, the Jordan frame and the Einstein frame, in which the Brans–Dicke theory, a prototype of generic scalar–tensor theory, can be formulated. There is a long standing debate on the physical equivalence of the formulations in these two different frames. It is shown here that gravitational deflection of light to second order accuracy may observationally distinguish the two versions of the Brans–Dicke theory.

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Field Independent Cosmic Evolution

Journal of Astrophysics ◽

10.1155/2013/590171 ◽

2013 ◽

Vol 2013 ◽

pp. 1-12 ◽

Cited By ~ 5

Author(s):

Nayem Sk ◽

Abhik Kumar Sanyal

Keyword(s):

Higher Order ◽

Noether Symmetry ◽

Scalar Tensor Theory ◽

Anisotropic Model ◽

Tachyonic Field ◽

Tensor Theory ◽

Cosmic Evolution ◽

Field Independent ◽

Conserved Current ◽

Theory Of Gravity

It has been shown earlier that Noether symmetry does not admit a form of corresponding to an action in which is coupled to scalar-tensor theory of gravity or even for pure theory of gravity taking anisotropic model into account. Here, we prove that theory of gravity does not admit Noether symmetry even if it is coupled to tachyonic field and considering a gauge in addition. To handle such a theory, a general conserved current has been constructed under a condition which decouples higher-order curvature part from the field part. This condition, in principle, solves for the scale-factor independently. Thus, cosmological evolution remains independent of the form of the chosen field, whether it is a scalar or a tachyon.

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GALACTIC AND ASTROPHYSICAL SIZES FROM SCALAR-TENSOR THEORY OF GRAVITY

International Journal of Modern Physics D ◽

10.1142/s0218271804004669 ◽

2004 ◽

Vol 13 (02) ◽

pp. 359-371 ◽

Cited By ~ 1

Author(s):

GIUSEPPE BASINI ◽

MARCO RICCI ◽

FULVIO BONGIORNO ◽

SALVATORE CAPOZZIELLO

Keyword(s):

Scalar Field ◽

Spiral Galaxies ◽

Weak Field ◽

Newtonian Potential ◽

Scalar Tensor Theory ◽

Field Limit ◽

Weak Field Limit ◽

Tensor Theory ◽

Flat Rotation Curves ◽

Theory Of Gravity

We investigate the weak-field limit of scalar-tensor theory of gravity and show that results are directly depending on the coupling and self-interaction potential of the scalar field. In particular, corrections are derived for the Newtonian potential. We discuss astrophysical applications of the results, in particular the flat rotation curves of spiral galaxies.

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