scholarly journals Clusters of Galaxies in a Weyl Geometric Approach to Gravity

2016 ◽  
Vol 2016 ◽  
pp. 1-22 ◽  
Author(s):  
Erhard Scholz
Keyword(s):  
Mass Distribution ◽  
Empirical Data ◽  
Total Mass ◽  
Geometric Approach ◽  
Einstein Gravity ◽  
Clusters Of Galaxies ◽  
Scalar Tensor Theory ◽  
Hot Gas ◽  
Tensor Theory ◽  
Baryonic Mass

A model for the dark halos of galaxy clusters, based on the Weyl geometric scalar tensor theory of gravity (WST) with a MOND-like approximation, is proposed. It is uniquely determined by the baryonic mass distribution of hot gas and stars. A first heuristic check against empirical data for 19 clusters (2 of which are outliers), taken from the literature, shows encouraging results. Modulo a caveat resulting from different background theories (Einstein gravity plus ΛCDM versus WST), the total mass for 15 of the outlier reduced ensemble of 17 clusters seems to be predicted correctly (in the sense of overlapping 1σ error intervals).

scholarly journals An ostentatious model of cosmological scalar–tensor theory

2019 ◽  
Vol 34 (19) ◽  
pp. 1950144 ◽  
Author(s):  
Nahomi Kan ◽  
Kiyoshi Shiraishi
Keyword(s):  
Einstein Gravity ◽  
Higher Order ◽  
Scalar Tensor Theory ◽  
Isotropic Universe ◽  
Tensor Theory ◽  
Cosmological Context ◽  
Higher Order Terms ◽  
Higher Order Derivative ◽  
Cosmological Scalar ◽  
Novel Model

We consider a novel model of gravity with a scalar field described by the Lagrangian with higher-order derivative terms in a cosmological context. The model has the same solution for the homogeneous and isotropic universe as in the model with the Einstein gravity, notwithstanding the additional higher-order terms. Finally, a possible modification scenario is briefly discussed.

CONSTRAINTS ON SCALAR-TENSOR COSMOLOGY FROM WMAP DATA

2011 ◽  
Vol 01 ◽  
pp. 183-188 ◽  
Author(s):  
RYO NAGATA
Keyword(s):  
Angular Spectrum ◽  
Quadratic Extension ◽  
Einstein Gravity ◽  
Gravity Theory ◽  
Observational Constraints ◽  
Scalar Tensor Theory ◽  
Tensor Theory ◽  
Wmap Data

We place observational constraints on a scalar-tensor gravity theory by comparing the WMAP temperature and polarization angular spectrum with its predictions. We examined the quadratic extension of Brans-Dicke theory and found that, even if the scalar-tensor theory was far from Einstein gravity in early cosmological epochs, CMB can set stringent constraints on the deviations from Einstein gravity.

Scalar fields in generalized theories of gravity: Limit to general relativity

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040006
Author(s):  
Piret Kuusk
Keyword(s):  
General Relativity ◽  
Scalar Fields ◽  
Einstein Gravity ◽  
Scalar Tensor Theory ◽  
Action Functional ◽  
Tensor Theory ◽  
General Action ◽  
Theories Of Gravity ◽  
Theory Of Gravitation ◽  
Special Case

The general action functional for a scalar-tensor theory of gravitation without derivative couplings is considered together with its special case of the Brans–Dicke theory. The aim of the paper is to clarify the problem of anomalous limit of the Brans–Dicke to the Einstein gravity.

scholarly journals Field Independent Cosmic Evolution

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
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.

Some results in the general scalar tensor theory

1984 ◽  
Vol 102 (2) ◽  
pp. 223-228
Author(s):  
Tarkeshwar Singh ◽  
T. Singh
Keyword(s):  
Scalar Tensor Theory ◽  
Tensor Theory ◽  
General Scalar

GALACTIC AND ASTROPHYSICAL SIZES FROM SCALAR-TENSOR THEORY OF GRAVITY

2004 ◽  
Vol 13 (02) ◽  
pp. 359-371 ◽  
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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