Model neutron stars with a constant scalar field in the bimetric scalar-tensor theory of gravitation. Different versions of the equation of state

Astrophysics ◽  
1998 ◽  
Vol 41 (2) ◽  
pp. 194-197
Author(s):  
L. Sh. Grigorian ◽  
P. F. Kazarian ◽  
H. F. Khachatrian
Keyword(s):  
Scalar Field ◽  
Equation Of State ◽  
Neutron Stars ◽  
Scalar Tensor Theory ◽  
Tensor Theory ◽  
Theory Of Gravitation

scholarly journals Non-Riemannian description of Robinson–Trautman spacetimes in Brans–Dicke theory of gravity

2019 ◽  
Vol 28 (04) ◽  
pp. 1950070
Author(s):  
Muzaffer Adak ◽  
Tekin Dereli ◽  
Yorgo Şenikoğlu
Keyword(s):  
Scalar Field ◽  
Differential Forms ◽  
Scalar Tensor Theory ◽  
Field Equations ◽  
Exterior Differential ◽  
Tensor Theory ◽  
Theory Of Gravitation ◽  
Theory Of Gravity ◽  
Future Reference

The variational field equations of Brans–Dicke scalar-tensor theory of gravitation are given in a non-Riemannian setting in the language of exterior differential forms over four-dimensional spacetimes. A conformally rescaled Robinson–Trautman metric together with the Brans–Dicke scalar field are used to characterize algebraically special Robinson–Trautman spacetimes. All the relevant tensors are worked out in a complex null basis and given explicitly in an appendix for future reference. Some special families of solutions are also given and discussed.

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

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.

Neutron stars in the bimetric Scalar-Tensor theory of gravitation. I. new solutions of the field equations

Astrophysics ◽  
1997 ◽  
Vol 40 (3) ◽  
pp. 252-259
Author(s):  
L. Sh. Grigorian ◽  
P. F. Kazarian ◽  
H. F. Khachatrian
Keyword(s):  
Neutron Stars ◽  
Scalar Tensor Theory ◽  
Field Equations ◽  
Tensor Theory ◽  
Theory Of Gravitation

The Large Numbers Hypothesis and a Relativistic Theory of Gravitation

1986 ◽  
Vol 39 (3) ◽  
pp. 339 ◽  
Author(s):  
YK Lau ◽  
SJ Prokhovnik
Keyword(s):  
Scalar Field ◽  
Scalar Potential ◽  
Cosmological Term ◽  
Time Dependent ◽  
Scalar Tensor Theory ◽  
Field Equations ◽  
Tensor Theory ◽  
Large Numbers ◽  
Dependent Form ◽  
Theory Of Gravitation

A way to reconcile Dirac's large numbers hypothesis and Einstein's theory of gravitation wasrecently suggested by Lau (1985). It is characterized by the conjecture of a time-dependentcosmological term and gravitational term in Einstein's field equations. Motivated by thisconjecture and the large numbers hypothesis, we formulate here a scalar-tensor theory in terms of an action principle. The cosmological term is required to be spatially dependent as well as time dependent in general. The theory developed is applied to a cosmological model compatible with the large numbers' hypothesis. The time-dependent form of the cosmological term and the scalar potential are then deduced. A possible explanation of the smallness of the cosmological term is also given and the possible significance of the scalar field is speculated.

scholarly journals Models of Compact Stars in the Bimetric Scalar-Tensor Theory of Gravitation

Particles ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 203-211 ◽  
Author(s):  
Levon Grigorian ◽  
Hrant Khachatryan ◽  
Aram Saharian
Keyword(s):  
General Relativity ◽  
Scalar Field ◽  
Coupling Function ◽  
Compact Stars ◽  
Spherically Symmetric ◽  
Scalar Tensor Theory ◽  
Metric Tensor ◽  
Tensor Theory ◽  
Theory Of Gravitation ◽  
The Masses

We investigate static spherically-symmetric configurations of gravitating masses in the bimetric scalar-tensor theory of gravitation. In the gravitational sector, the theory contains the metric tensor, a scalar field and a background metric as an absolute variable of the theory. The analysis is presented for the simplest version of the theory with a constant coupling function and a zero cosmological function. We show that, depending on the value of the theory parameter, the masses for superdense compact configurations can be essentially larger compared to the configurations in general relativity.

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