scholarly journals Bulk viscous string cosmological models in f(R) gravity

2018 ◽  
Vol 96 (1) ◽  
pp. 55-61 ◽  
Author(s):  
M. Vijaya Santhi ◽  
V.U.M. Rao ◽  
Y. Aditya
Keyword(s):  
Bianchi Type ◽  
Cosmic Strings ◽  
Cosmological Models ◽  
Hubble’S Parameter ◽  
Field Equations ◽  
One Dimensional ◽  
Physical Conditions ◽  
Bulk Viscous Fluid ◽  
Bulk Viscous ◽  
Spatially Homogeneous

In this paper, we derive f(R) gravity field equations with the help of a spatially homogeneous and anisotropic Bianchi type-III space–time, in the presence of a bulk viscous fluid, containing one-dimensional cosmic strings. Here we obtained the solutions of the field equations, both in the presence and in the absence of cosmic strings, under some specific plausible physical conditions. In particular, cosmological models with bulk viscous strings in f(R) theory of gravity are obtained by using the special law of variation for Hubble’s parameter proposed by Berman (Nuovo Cimento, B74, 182 (1983)). Various physical and kinematical properties of the models are also discussed.

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.

scholarly journals Anisotropic Bulk Viscous String Cosmological Model in a Scalar-Tensor Theory of Gravitation

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
D. R. K. Reddy ◽  
Ch. Purnachandra Rao ◽  
T. Vidyasagar ◽  
R. Bhuvana Vijaya
Keyword(s):  
Equations Of State ◽  
Momentum Tensor ◽  
Scalar Tensor Theory ◽  
Field Equations ◽  
Physical Conditions ◽  
Bulk Viscous Fluid ◽  
Tensor Theory ◽  
Highly Nonlinear ◽  
Bulk Viscous ◽  
Theory Of Gravitation

Spatially homogeneous, anisotropic, and tilted Bianchi type-VI0model is investigated in a new scalar-tensor theory of gravitation proposed by Saez and Ballester (1986) when the source for energy momentum tensor is a bulk viscous fluid containing one-dimensional cosmic strings. Exact solution of the highly nonlinear field equations is obtained using the following plausible physical conditions: (i) scalar expansion of the space-time which is proportional to the shear scalar, (ii) the barotropic equations of state for pressure and energy density, and (iii) a special law of variation for Hubble’s parameter proposed by Berman (1983). Some physical and kinematical properties of the model are also discussed.

AN EXACT BIANCHI TYPE-I COSMOLOGICAL MODEL IN LYRA'S MANIFOLD

2008 ◽  
Vol 23 (06) ◽  
pp. 813-822 ◽  
Author(s):  
SURESH KUMAR ◽  
C. P. SINGH
Keyword(s):  
Bianchi Type ◽  
Type I ◽  
Hubble’S Parameter ◽  
Field Equations ◽  
Bianchi Type I ◽  
Lyra’S Manifold ◽  
Type Ia ◽  
Lyra’S Geometry ◽  
Spatially Homogeneous ◽  
Ia Supernovae

A spatially homogeneous and anisotropic Bianchi type-I space–time has been studied within the framework of Lyra's geometry. Exact solutions of the Einstein's field equations have been obtained with a time dependent gauge function by using a special law of variation for Hubble's parameter that yields a constant value of deceleration parameter. It has been found that the solutions generalize the solutions obtained by Rahaman et al. [Astrophys. Space Sci.299, 211 (2005)] and are consistent with the recent observations of type Ia supernovae. A detailed study of physical and kinematical properties of the model has been carried out.

scholarly journals Anisotropic Bianchi Type-III Bulk Viscous Fluid Universe in Lyra Geometry

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Priyanka Kumari ◽  
M. K. Singh ◽  
Shri Ram
Keyword(s):  
Cosmological Model ◽  
Viscous Fluid ◽  
Bianchi Type ◽  
Lyra Geometry ◽  
Scale Factor ◽  
Field Equations ◽  
Type Iii ◽  
Bulk Viscous Fluid ◽  
Bulk Viscous ◽  
The Universe

An anisotropic Bianchi type-III cosmological model is investigated in the presence of a bulk viscous fluid within the framework of Lyra geometry with time-dependent displacement vector. It is shown that the field equations are solvable for any arbitrary function of a scale factor. To get the deterministic model of the universe, we have assumed that (i) a simple power-law form of a scale factor and (ii) the bulk viscosity coefficient are proportional to the energy density of the matter. The exact solutions of the Einstein’s field equations are obtained which represent an expanding, shearing, and decelerating model of the universe. Some physical and kinematical behaviors of the cosmological model are briefly discussed.

Bianchi types I and V bulk viscous fluid cosmological models in f(R, T) gravity theory

Open Physics ◽  
2014 ◽  
Vol 12 (10) ◽  
Author(s):  
Shri Ram ◽  
Priyanka Kumari
Keyword(s):  
Viscous Fluid ◽  
Cosmological Models ◽  
Gravity Theory ◽  
Field Equations ◽  
Bulk Viscous Fluid ◽  
Bulk Viscous ◽  
Special Value ◽  
The Universe ◽  
Average Scale Factor ◽  
Bianchi Types

AbstractIn this paper we present non-singular Bianchi types I and V cosmological models, in the presence of bulk viscous fluid and within the framework of f(R,T) gravity theory. Exact solutions to the field equations are obtained by choosing a particular form of the function f(R,T) and a special value for the average scale factor of the model, which corresponds to a time- dependent deceleration parameter. The cosmological models initially accelerate for a certain period of time and thereafter decelerate. The physical and kinematical properties of the models of the universe are discussed.

scholarly journals Bianchi Type V Universe and Bulk Viscous Models with Time Dependent Gravitational Constant and Cosmological Constant in General Relativity

2019 ◽  
Vol 9 (1S3) ◽  
pp. 251-256
Keyword(s):  
General Relativity ◽  
Cosmological Constant ◽  
Gravitational Constant ◽  
Bianchi Type ◽  
Relativity Theory ◽  
Field Equations ◽  
Bulk Viscous Fluid ◽  
Bulk Viscous ◽  
Viscous Models ◽  
Bianchi Type V Universe

This paper deals with Bulk Viscous Models and Bianchi type- universe in the standard general relativity theory by assuming where constants, is the density. Einstein field equations ( ) have been solved in the presence of a variable gravitational constant as well as a variable cosmological constant together with a bulk viscous fluid. In order to find a deterministic solution of EFEs, a simple form of Hubble parameter being constant when where has been considered here that shows the signature flip from early deceleration to present acceleration. Moreover, the bulk viscous coefficient is allowed to vary with the density as . The physical and geometrical behavior are described in detail for the obtained model. The model obtained here is in good agreement with the present cosmological observations.

Sign in / Sign up

Export Citation Format

Share Document