scholarly journals Bianchi type-VI0 modified holographic Ricci dark energy model in a scalar–tensor theory

2017 ◽  
Vol 95 (2) ◽  
pp. 179-183 ◽  
Author(s):  
M. Vijaya Santhi ◽  
V.U.M. Rao ◽  
Y. Aditya
Keyword(s):  
Dark Energy ◽  
Bianchi Type ◽  
Scalar Tensor Theory ◽  
Field Equations ◽  
Ricci Dark Energy ◽  
Tensor Theory ◽  
Expansion Scalar ◽  
Shear Scalar ◽  
Average Scale Factor ◽  
Good Agreement

In this paper, we consider Bianchi type-VI0 space–time filled with anisotropic modified holographic Ricci dark energy in a scalar–tensor theory proposed by Brans–Dicke (Phys. Rev. 124, 925 (1961)). The field equations in this scalar–tensor theory, have been solved for the following physically relevant assumptions: (i) the scalar field ([Formula: see text]) is proportional to average scale factor (a(t)), (ii) expansion scalar (θ) in the model is proportional to shear scalar (σ). It has been observed that the presented universe is in an accelerating phase at the present epoch, which is in good agreement with the recent astronomical observations. We have also discussed some other properties of the obtained model.

Bianchi type VI0 generalized ghost pilgrim dark energy model in Brans–Dicke theory of gravitation

2016 ◽  
Vol 94 (10) ◽  
pp. 1040-1044 ◽  
Author(s):  
V.U.M. Rao ◽  
U.Y. Divya Prasanthi
Keyword(s):  
Dark Energy ◽  
Bianchi Type ◽  
Field Equations ◽  
Pilgrim Dark Energy ◽  
Geometrical Properties ◽  
Scalar Expansion ◽  
Theory Of Gravitation ◽  
Shear Scalar ◽  
Bianchi Type Vi0 ◽  
Average Scale Factor

In this paper, we solve Brans–Dicke (BD) theory (Phys. Rev. D, 24, 925) field equations for anisotropic Bianchi type VI0 space–time and discuss evolution of the expanding Universe. Here, we consider pressureless fluid and isotropic generalized ghost pilgrim dark energy as the source of matter and dark energy, respectively. To get the determinate solution of the field equations we have used (i) scalar expansion proportional to the shear scalar and (ii) scalar field (in BD theory) proportional to average scale factor of the model. Some physical and geometrical properties of the model are also discussed.

Holographic dark energy model in Bianchi type VI0 Universe in a scalar–tensor theory of gravitation with hybrid expansion law

2016 ◽  
Vol 94 (12) ◽  
pp. 1338-1343 ◽  
Author(s):  
D.R.K. Reddy ◽  
S. Anitha ◽  
S. Umadevi
Keyword(s):  
Dark Energy ◽  
Bianchi Type ◽  
Holographic Dark Energy ◽  
Space Time ◽  
Scalar Tensor Theory ◽  
Field Equations ◽  
Tensor Theory ◽  
Theory Of Gravitation ◽  
The Universe ◽  
Energy Components

In this paper, we have obtained field equations of Sáez–Ballester (Phys. Lett. A, 113, 467 (1986)) scalar–tensor theory in the presence of two minimally interacting fields; matter and holographic dark energy components in the space–time described by a spatially homogeneous and anisotropic Bianchi type VI0 space–time. We have used the hybrid expansion law, proposed by Akarsu et al. (JCAP, 01, 022 (2014)), to obtain a determinate solution of the field equations. This solution represents a minimally interacting Bianchi type VI0 Sáez–Ballester universe. Physical and kinematical properties of the universe are also studied.

Cosmological constant Λ in f(R,T) modified gravity

2016 ◽  
Vol 13 (05) ◽  
pp. 1650058 ◽  
Author(s):  
Gyan Prakash Singh ◽  
Binaya Kumar Bishi ◽  
Pradyumn Kumar Sahoo
Keyword(s):  
Cosmological Model ◽  
Cosmological Constant ◽  
Modified Gravity ◽  
Bianchi Type ◽  
Field Equations ◽  
Type Iii ◽  
Expansion Scalar ◽  
Modified Theory Of Gravity ◽  
Shear Scalar ◽  
Modified Theory

In this paper, we have studied the Bianchi type-III cosmological model in the presence of cosmological constant in the context of [Formula: see text] modified theory of gravity. Here, we have discussed two classes of [Formula: see text] gravity, i.e. [Formula: see text] and [Formula: see text]. In both classes, the modified field equations are solved by the relation expansion scalar [Formula: see text] that is proportional to shear scalar [Formula: see text] which gives [Formula: see text], where [Formula: see text] and [Formula: see text] are metric potentials. Also we have discussed some physical and kinematical properties of the models.

Anisotropic Bianchi type-II modified holographic Ricci dark energy model in scale-covariant theory of gravitation

2021 ◽  
Author(s):  
Shri Ram ◽  
S. Chandel ◽  
M.K. Verma
Keyword(s):  
Dark Energy ◽  
Bianchi Type ◽  
Covariant Theory ◽  
Type Ii ◽  
Field Equations ◽  
Ricci Dark Energy ◽  
Scale Covariant Theory ◽  
Cosmological Observations ◽  
Negative Constant ◽  
Theory Of Gravitation

In this paper, we obtain an anisotropic Bianchi type-II space-time with dark matter and the modified holographic Ricci dark energy in the scale-covariant theory of gravitation. Exact solutions of the field equations are obtained by assuming (I) a negative constant value of the deceleration parameter (II) the component σ<sup>1</sup><sub>1</sub> of the shear tensor σ<sup>j</sup><sub>i</sub> is proportional to the mean Hubble parameter and (III) the gauge function Φ is proportional to a power function of the average scale factor. We have also discussed some important physical aspects of the model which is in agreement with the modern cosmological observations.

scholarly journals Anisotropic magnetized holographic Ricci dark energy cosmological models

2017 ◽  
Vol 95 (4) ◽  
pp. 381-392 ◽  
Author(s):  
M. Vijaya Santhi ◽  
V.U.M. Rao ◽  
Y. Aditya
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Deceleration Parameter ◽  
Bianchi Type ◽  
Cosmological Models ◽  
Field Equations ◽  
Ricci Dark Energy ◽  
Theor Phys ◽  
Linearly Varying Deceleration Parameter ◽  
Spatially Homogeneous

In this paper, we have considered spatially homogeneous and anisotropic Bianchi type-III space–time filled with matter and anisotropic modified holographic Ricci dark energy in general relativity. We have solved Einstein’s field equations using the following possibilities: (i) hybrid expansion law proposed by Akarsu et al. (JCAP, 01, 022 (2014)); (ii) a varying deceleration parameter considered by Mishra et al. (Int. J. Theor. Phys. 52, 2546 (2013)); and (iii) a linearly varying deceleration parameter given by Akarsu and Dereli (Int. J. Theor. Phys. 51, 612 (2012)). We have presented the cosmological models in each of the preceding cases and studied their evolutions. We have also discussed physical and kinematical properties of the models.

Bianchi type-II universe with linear equation of state

Open Physics ◽  
2014 ◽  
Vol 12 (8) ◽  
Author(s):  
Kishor Adhav ◽  
Ishwar Pawade ◽  
Abhijit Bansod
Keyword(s):  
General Relativity ◽  
Equation Of State ◽  
Cosmological Model ◽  
Linear Equation ◽  
Bianchi Type ◽  
Type Ii ◽  
Field Equations ◽  
Expansion Scalar ◽  
Shear Scalar

AbstractWe have studied anisotropic and homogeneous Bianchi type-II cosmological model with linear equation of state (EoS) p = αρ−β, where α and β are constants, in General Relativity. In order to obtain the solutions of the field equations we have assumed the geometrical restriction that expansion scalar θ is proportional to shear scalar σ. The geometrical and physical aspects of the model are also studied.

scholarly journals Kantowski–Sachs modified holographic Ricci dark energy model in Saez–Ballester theory of gravitation

2018 ◽  
Vol 96 (5) ◽  
pp. 555-559 ◽  
Author(s):  
M.P.V.V. Bhaskar Rao ◽  
D.R.K. Reddy ◽  
K. Sobhan Babu
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Field Equations ◽  
Ricci Dark Energy ◽  
Dark Energy Density ◽  
Physical Behavior ◽  
Tensor Theory ◽  
Theory Of Gravitation ◽  
Kinematical Parameters ◽  
Energy Components

We have considered Kantowski–Sachs space–time in the presence of matter and anisotropic modified holographic Ricci dark energy components in the scalar–tensor theory of gravitation formulated by Saez and Ballester (Phys. Lett. A, 113, 467, 1986) and derived the field equations of the theory. We have used (i) hybrid expansion law proposed by Akarsu et al. (JCAP, 022, 2014), (ii) a relation between metric potentials, and (iii) modified holographic Ricci dark energy density given by Chen and Jing (Phys. Lett. B, 679, 144, 2009) to obtain an exact solution of the field equations that describes a Kantowski–Sachs holographic modified Ricci dark energy universe in this theory. Physical and kinematical parameters are also computed and their physical behavior is discussed.

Magnetized anisotropic dark energy cosmological models in scale covariant theory of gravitation

2014 ◽  
Vol 23 (07) ◽  
pp. 1450065 ◽  
Author(s):  
S. D. Katore ◽  
M. M. Sancheti ◽  
S. P. Hatkar
Keyword(s):  
Dark Energy ◽  
Bianchi Type ◽  
Covariant Theory ◽  
Type Ii ◽  
Field Equations ◽  
Scale Covariant Theory ◽  
Anisotropic Dark Energy ◽  
Expansion Scalar ◽  
Viii And Ix ◽  
Theory Of Gravitation

In the present paper, we have investigated Bianchi type II, VIII and IX spacetime in the presence of magnetized anisotropic dark energy in the Scale covariant theory of gravitation. Exact solution of the field equations are obtained by assuming the expansion anisotropy (the ratio of shear scalar to expansion scalar) to be a function of average scale factor. The isotropy of the fluid, space and expansion are examined.

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