ANISOTROPIC BIANCHI-V PERFECT FLUID SPACE–TIME WITH VARIABLES G AND Λ

2010 ◽  
Vol 25 (18n19) ◽  
pp. 3825-3834 ◽  
Author(s):  
C. P. SINGH ◽  
A. BEESHAM
Keyword(s):  
Perfect Fluid ◽  
Deceleration Parameter ◽  
Particle Creation ◽  
Big Bang ◽  
Initial Time ◽  
Field Equations ◽  
Constant Deceleration Parameter ◽  
Anisotropic Parameter ◽  
Bianchi V ◽  
Variable G

We study spatially homogeneous and anisotropic Bianchi-V perfect fluid cosmological model with variable G and Λ. Exact solutions to the field equations in the case of particle creation and in the absence of particle creation are obtained by assuming a constant deceleration parameter. The model has a big-bang-type singularity at the initial time t = 0. We find that a constant value of deceleration parameter is reasonable for a description of the present day universe. We also observe that the variable G does not necessarily imply particle creation. The behavior of observationally important parameters such as the expansion scalar, mean anisotropic parameter and shear scalar are discussed. It is observed that the solutions are compatible with the results of recent observations.

BIANCHI TYPE V COSMOLOGICAL MODELS WITH PERFECT FLUID AND HEAT CONDUCTION IN LYRA'S GEOMETRY

2008 ◽  
Vol 23 (31) ◽  
pp. 4991-5005 ◽  
Author(s):  
SHRI RAM ◽  
MOHD. ZEYAUDDIN ◽  
C. P. SINGH
Keyword(s):  
Perfect Fluid ◽  
Bianchi Type ◽  
Displacement Vector ◽  
Hubble’S Parameter ◽  
Field Equations ◽  
Constant Deceleration Parameter ◽  
Displacement Vector Field ◽  
Lyra’S Geometry ◽  
Type V ◽  
Bianchi Type V

The field equations within the framework of Lyra's geometry with a time-dependent displacement vector field for a Bianchi type-V space–time filled with a perfect fluid and heat flow are presented. Two different classes of physically viable solutions are obtained by using a special law of variation for the generalized mean Hubble's parameter which correspond to singular and nonsingular models with constant deceleration parameter. These models are found to be consistent with the observations on the present day universe. Some thermodynamical relations are studied. The physical and kinematical behaviors of the models are also discussed.

BIANCHI TYPE-II COSMOLOGICAL MODELS WITH CONSTANT DECELERATION PARAMETER

2006 ◽  
Vol 15 (03) ◽  
pp. 419-438 ◽  
Author(s):  
C. P. SINGH ◽  
SURESH KUMAR
Keyword(s):  
Deceleration Parameter ◽  
Bianchi Type ◽  
Physical Models ◽  
Type Ii ◽  
Anisotropic Space ◽  
Hubble’S Parameter ◽  
Field Equations ◽  
Constant Deceleration Parameter ◽  
Exponential Expansion ◽  
Rotationally Symmetric

A special law of variation for Hubble's parameter in anisotropic space–time models that yields a constant value of the deceleration parameter is presented. Also, a spatially homogeneous and anisotropic but locally rotationally symmetric (LRS) Bianchi type-II cosmological model is studied with a perfect fluid and constant deceleration parameter. Assuming the equation of state p = γρ, where 0≤γ≤1, and using a special law of variation for the Hubble parameter, we are able to construct many new solutions to Einstein's field equations of LRS Bianchi type-II for four different physical models (dust, radiation, Zel'dovich and vacuum). We discuss the solutions with power-law and exponential expansion and examine a particular class of models. A detailed study of kinematic, geometrical and observational properties is carried out.

ANISOTROPIC BIANCHI-V COSMOLOGICAL MODELS IN SAEZ–BALLESTER THEORY OF GRAVITATION

2008 ◽  
Vol 23 (18) ◽  
pp. 2719-2731 ◽  
Author(s):  
C. P. SINGH ◽  
MOHD. ZEYAUDDIN ◽  
SHRI RAM
Keyword(s):  
Deceleration Parameter ◽  
Cosmological Models ◽  
Luminosity Distance ◽  
Hubble’S Parameter ◽  
Field Equations ◽  
Tensor Theory ◽  
Look Back ◽  
Bianchi V ◽  
Theory Of Gravitation ◽  
The Universe

A general approach for investigating Bianchi-V cosmological models is introduced in a scalar-tensor theory of gravitation proposed by Saez and Ballester in which the law of variation for Hubble's parameter is taken into account. This variation for Hubble's parameter that yields a constant value of deceleration parameter is then utilized to solve the field equations governing anisotropic Bianchi-V space–time filled with perfect fluid. Two types of exact solutions that correspond to singular and nonsingular models are presented. Finally, we arrive to the conclusion that the universe decelerates for positive value of deceleration parameter whereas it accelerates for negative one. The behaviors of observationally important parameters are discussed in detail. Exact expressions for look-back time, luminosity distance and event horizon versus redshift are derived and their significance are discussed in detail. It has been observed that the solutions are compatible with the results of recent observations.

scholarly journals A cosmology with variable c

2006 ◽  
Vol 84 (10) ◽  
pp. 933-944 ◽  
Author(s):  
H Shojaie ◽  
M Farhoudi
Keyword(s):  
Cosmological Model ◽  
Dynamic Equation ◽  
Deceleration Parameter ◽  
Energy Momentum Tensor ◽  
Energy Content ◽  
Big Bang ◽  
Momentum Tensor ◽  
Constant Deceleration Parameter ◽  
Extra Energy ◽  
The Universe

A new varying-c cosmological model, constructed using two additional assumptions, which was introduced in our previous work, is briefly reviewed and the dynamic equation of the model is derived distinctly from a semi-Newtonian approach. The results of this model, using a [Formula: see text] term and an extra energy-momentum tensor, are considered separately. It is shown that the Universe began from a hot Big Bang and expands forever with a constant deceleration parameter regardless of its curvature. Finally, the age, the radius, and the energy content of the Universe are estimated and some discussion about the type of the geometry of the Universe is provided. PACS Nos.: 98.80.Bp, 98.80.Jk

Bianchi type I and V solutions in f(R, T) gravity with time-dependent deceleration parameter

2016 ◽  
Vol 94 (12) ◽  
pp. 1289-1296 ◽  
Author(s):  
M. Zubair ◽  
Syed M. Ali Hassan ◽  
G. Abbas
Keyword(s):  
Deceleration Parameter ◽  
Bianchi Type ◽  
Energy Condition ◽  
Null Energy Condition ◽  
Momentum Tensor ◽  
Type I ◽  
Field Equations ◽  
Bianchi Type I ◽  
Bianchi V ◽  
Type V

In this paper, our attention is to reconstruct an appropriate model for Bianchi type I and Bianchi V space–times in f(R, T) gravity with the help of special law of deceleration parameter in connection to f(R, T) gravity (where R is the Ricci scalar and T is the trace of energy–momentum tensor). We solve the modified Einstein field equations for anisotropic and homogeneous Bianchi type V space–time. The solution of field equations facilitates finding out the physical as well as kinematical quantities. We explore the behavior of null energy condition, energy density, and deceleration parameter to present cosmic picture.

scholarly journals Magnetized strange quark model with Big Rip singularity in f(R, T) gravity

2017 ◽  
Vol 32 (21) ◽  
pp. 1750105 ◽  
Author(s):  
P. K. Sahoo ◽  
Parbati Sahoo ◽  
Binaya K. Bishi ◽  
S. Aygün
Keyword(s):  
Observational Data ◽  
Deceleration Parameter ◽  
Strange Quark ◽  
Big Bang ◽  
Distance Modulus ◽  
Type I ◽  
Field Equations ◽  
Big Rip ◽  
Standard Cosmology ◽  
Rotationally Symmetric

Locally rotationally symmetric (LRS) Bianchi type-I magnetized strange quark matter (SQM) cosmological model has been studied based on f(R, T) gravity. The exact solutions of the field equations are derived with linearly time varying deceleration parameter, which is consistent with observational data (from SNIa, BAO and CMB) of standard cosmology. It is observed that the model begins with big bang and ends with a Big Rip. The transition of the deceleration parameter from decelerating phase to accelerating phase with respect to redshift obtained in our model fits with the recent observational data obtained by Farook et al. [Astrophys. J. 835, 26 (2017)]. The well-known Hubble parameter H(z) and distance modulus [Formula: see text](z) are discussed with redshift.

scholarly journals KALUZA - KLEIN COSMOLOGICAL MODEL WITH QUARK AND STRANGE QUARK MATTER INF(R,T)GRAVITY

2021 ◽  
Vol 9 (04) ◽  
pp. 264-271
Author(s):  
Samadhan L. Munde ◽  
Keyword(s):  
Cosmological Model ◽  
Quark Matter ◽  
Deceleration Parameter ◽  
Strange Quark ◽  
Space Time ◽  
Strange Quark Matter ◽  
Field Equations ◽  
Constant Deceleration Parameter ◽  
General Solutions ◽  
Kaluza Klein

In this paper,Kaluza-Klein space-time with quark and strange quark matter in gravity has been considered. The general solutions of the field equations of Kaluza-Klein space-time have been obtained under the assumption of constant deceleration parameter. The physical and geometrical aspects of the model are also discussed in details.

scholarly journals On the stability of Einstein universe in f(R, T, Rμν Tμν) gravity

2018 ◽  
Vol 33 (36) ◽  
pp. 1850216 ◽  
Author(s):  
M. Sharif ◽  
Arfa Waseem
Keyword(s):  
State Parameter ◽  
Big Bang ◽  
Graphical Analysis ◽  
Momentum Tensor ◽  
Field Equations ◽  
Einstein Universe ◽  
Existence And Stability ◽  
The Stability ◽  
The Big Bang ◽  
Big Bang Singularity

This paper investigates the existence and stability of Einstein universe in the context of f(R, T, Q) gravity, where Q = R[Formula: see text] T[Formula: see text]. Considering linear homogeneous perturbations around scale factor and energy density, we formulate static as well as perturbed field equations. We parametrize the stability regions corresponding to conserved as well as non-conserved energy–momentum tensor using linear equation of state parameter for particular models of this gravity. The graphical analysis concludes that for a suitable choice of parameters, stable regions of the Einstein universe are obtained which indicates that the big bang singularity can be avoided successfully by the emergent mechanism in non-minimal matter-curvature coupled gravity.

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