scholarly journals Bianchi Type- I Bulk Viscosity with a DE Cosmological Model

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Daba Meshesha Gusu
Keyword(s):  
Dark Energy ◽  
Cosmological Model ◽  
Bulk Viscosity ◽  
Bianchi Type ◽  
Early Time ◽  
Observational Result ◽  
Type I ◽  
Field Equations ◽  
Geometrical Properties ◽  
The Universe

The finding article presents Bianchi type- I universe in the presence of bulk viscous and DE fluid nature of a cosmological model. The solutions of field equations were obtained by assuming hybrid expansion law. The physical significance of the obtained findings illustrates the dominance of bulk viscosity in early and dominance of dark energy fluid emergences in late. This leads to indicate the presence of bulk viscosity nature more effective in early time rather than late times, and also, it shows the dominance of dark energy in late times which grants the current observational result of the universe. Certain physical and geometrical properties of the model are also discussed.

Phase transition of LRS Bianchi type-I cosmological model in f(R,T) gravity

2020 ◽  
Vol 17 (12) ◽  
pp. 2050187
Author(s):  
R. K. Tiwari ◽  
D. Sofuoğlu ◽  
V. K. Dubey
Keyword(s):  
Cosmological Model ◽  
Bianchi Type ◽  
Early Time ◽  
Momentum Tensor ◽  
Late Time ◽  
Type I ◽  
Field Equations ◽  
Bianchi Type I ◽  
Accelerating Expansion ◽  
Acceleration Of The Universe

In this work, LRS Bianchi type-I cosmological model with perfect fluid source in [Formula: see text] gravity theory, where [Formula: see text] is the Ricci scalar and [Formula: see text] is the trace of the stress energy-momentum tensor, has been studied in order to investigate early time deceleration and late time acceleration of the universe. By proposing a new special form of time-varying deceleration parameter in terms of Hubble parameter, the exact solution of the field equations has been obtained. The physical and geometric quantities of the model have been derived and their evolution has been discussed. Our model has an initial singularity and initially exhibits decelerating expansion and transits to accelerating expansion phase at last eras. The nature of the matter source of the model is consistent with the standard model in frame of the structure formation.

Cosmological model with variable deceleration parameter in f(R,T) modified gravity

2018 ◽  
Vol 15 (07) ◽  
pp. 1850115 ◽  
Author(s):  
Rishi Kumar Tiwari ◽  
Aroonkumar Beesham ◽  
Bhupendra Shukla
Keyword(s):  
Cosmological Model ◽  
Modified Gravity ◽  
Deceleration Parameter ◽  
Late Time ◽  
Type I ◽  
Field Equations ◽  
Geometrical Properties ◽  
Deceleration Phase ◽  
Modified Gravity Theory ◽  
The Universe

A study is made of the LRS Bianchi type-I cosmological model in [Formula: see text] modified gravity theory. Einstein’s field equations in [Formula: see text] gravity are solved by taking [Formula: see text] and the deceleration parameter [Formula: see text] to be a linear function of the Hubble parameter [Formula: see text]. The universe begins with an initial singular state and changes with time from an early deceleration phase to a late time acceleration phase. We have found that the jerk parameter [Formula: see text] in the model approaches that of the [Formula: see text] model at late times. We also discuss the physical and geometrical properties of the model.

scholarly journals LOCALLY ROTATIONALLY SYMMETRIC BIANCHI TYPE-I COSMOLOGICAL MODEL IN f(T) GRAVITY: FROM EARLY TO DARK ENERGY DOMINATED UNIVERSE

2014 ◽  
Vol 23 (01) ◽  
pp. 1450004 ◽  
Author(s):  
M. E. RODRIGUES ◽  
I. G. SALAKO ◽  
M. J. S. HOUNDJO ◽  
J. TOSSA
Keyword(s):  
Dark Energy ◽  
Cosmological Model ◽  
Dark Energy Model ◽  
Bianchi Type ◽  
Rotational Symmetry ◽  
Type I ◽  
Bianchi Type I ◽  
Reconstruction Scheme ◽  
Rotationally Symmetric ◽  
The Universe

We study the locally rotational symmetry Bianchi type-I dark energy model in the framework of f(T) theory of gravity, where T denotes the torsion scalar. A viable cosmological model is undertaken and the isotropization of this latter is checked, yielding a result that reflects the real evolution of our universe. Moreover, still in the anisotropic optic, a more complicated f(T) model is obtained from the cosmological reconstruction scheme and the analysis shows that the universe is more anisotropic at the beginning if the terms of higher order in T are not considered. This means that the nonlinear model should be favored by observational data.

scholarly journals Bianchi Type-VI0 Cosmological Model with Special Form of Scale Factor in Sen-Dunn Theory of Gravitation

2021 ◽  
Vol 13 (1) ◽  
pp. 137-143
Author(s):  
D. Basumatay ◽  
M. Dewri
Keyword(s):  
Cosmological Model ◽  
Special Form ◽  
Bianchi Type ◽  
Scale Factor ◽  
Type I ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Geometrical Properties ◽  
Theory Of Gravitation ◽  
Bianchi Type Vi0

A Bianchi Type-VI0 cosmological model with a special form of scale factor is studied. Einstein field equations in Sen-Dunn theory are obtained and solved for exact solutions. This solution gives a scenario of the dark energy model which tends to a ɅCDM model. The physical and geometrical properties are also obtained and analyzed with the present day observations.

Bianchi type I cosmological model with perfect fluid and string in f(T) theory of gravitation

2020 ◽  
Vol 29 (08) ◽  
pp. 2050054
Author(s):  
V. R. Chirde ◽  
S. P. Hatkar ◽  
S. D. Katore
Keyword(s):  
Dark Energy ◽  
Perfect Fluid ◽  
Bianchi Type ◽  
Type I ◽  
Field Equations ◽  
Bianchi Type I ◽  
Functional Forms ◽  
Theory Of Gravitation ◽  
Shear Scalar ◽  
The Universe

We have studied LRS Bianchi type I cosmological models with barotropic perfect fluid and cosmic string in the framework of [Formula: see text] theory of gravitation. We have assumed that expansion of the model is proportional to the shear scalar. Hybrid law of expansion is also used to solve the field equations. Three different functional forms of the function [Formula: see text] such as [Formula: see text] [Formula: see text] and [Formula: see text] are chosen for investigation. It is observed that the universe is dominated by quintessence type dark energy. The universe is accelerating, expanding and anisotropic.

scholarly journals Mixed fluid cosmological model in f(R, T) gravity

2020 ◽  
Vol 98 (11) ◽  
pp. 1015-1022 ◽  
Author(s):  
Parbati Sahoo ◽  
Barkha Taori ◽  
K.L. Mahanta
Keyword(s):  
Cosmological Model ◽  
Bianchi Type ◽  
Type I ◽  
Time Varying ◽  
Eos Parameter ◽  
Barotropic Fluid ◽  
Rotationally Symmetric ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Mixed Fluid

We construct a locally rotationally symmetric (LRS) Bianchi type-I cosmological model in f(R, T) theory of gravity when the source of gravitation is a mixture of barotropic fluid and dark energy (DE) by employing a time-varying deceleration parameter. We observe through the behavior of the state finder parameters (r, s) that our model begins from the Einstein static era and goes to ΛCDM era. The equation of state (EOS) parameter (ωd) for DE varies from the phantom (ω < –1) phase to quintessence (ω > –1) phase, which is consistent with observational results. It is found that the discussed model can reproduce the current accelerating phase of the expansion of the universe.

scholarly journals Bianchi type–I Model with Time Varying Λ and G: The Generalized Solution

2020 ◽  
Vol 29 (1) ◽  
pp. 89-93
Author(s):  
Alnadhief H. A. Alfedeel
Keyword(s):  
Analytical Solution ◽  
Bianchi Type ◽  
Generalized Solution ◽  
Type I ◽  
Time Varying ◽  
Field Equations ◽  
Geometric Function ◽  
Varying Λ ◽  
The Universe ◽  
Average Scale Factor

AbstractIn this paper, we have investigated the homogeneous and anisotropic Bianchi type–I cosmological model with a time-varying Newtonian and cosmological constant. We have analytically solved Einstein’s field equations (EFEs) in the presence of a stiff-perfect fluid. We show that the analytical solution for the average scale factor for the generalized Friedman equation involves the hyper-geometric function. We have studied the physical and kinematical quantities of the model, and it is found that the universe becomes isotropic at late times.

scholarly journals Interaction of Bianchi type-I anisotropic cloud string cosmological model universe with electromagnetic field

2020 ◽  
Vol 17 (09) ◽  
pp. 2050133
Author(s):  
Kangujam Priyokumar Singh ◽  
Mahbubur Rahman Mollah ◽  
Rajshekhar Roy Baruah ◽  
Meher Daimary
Keyword(s):  
Electromagnetic Field ◽  
Cosmological Model ◽  
Bianchi Type ◽  
Physical Parameters ◽  
Type I ◽  
Field Equations ◽  
Rest Energy ◽  
Model Universe ◽  
Bianchi Type I ◽  
String Cosmological Model

Here, we have investigated the interaction of Bianchi type-I anisotropic cloud string cosmological model universe with electromagnetic field in the context of general relativity. In this paper, the energy-momentum tensor is assumed to be the sum of the rest energy density and string tension density with an electromagnetic field. To obtain exact solution of Einstein’s field equations, we take the average scale factor as an integrating function of time. Also, the dynamics and significance of various physical parameters of model are discussed.

Anisotropic Dark Energy Cosmological Model with Cosmic Strings

2020 ◽  
Author(s):  
T. Vinutha ◽  
V.U.M. Rao ◽  
Molla Mengesha
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Cosmological Model ◽  
State Parameter ◽  
Accelerated Expansion ◽  
Physical Parameters ◽  
Type I ◽  
Field Equations ◽  
Eos Parameter ◽  
Phantom Divide

The present study deals with a spatially homogeneous locally rotationally symmetric (LRS) Bianchi type-I dark energy cosmological model containing one dimensional cosmic string fluid source. The Einstein's field equations are solved by using a relation between the metric potentials and hybrid expansion law of average scale factor. We discuss accelerated expansion of our model through equation of state (ωde) and deceleration parameter (q). We observe that in the evolution of our model, the equation of state parameter starts from matter dominated phase ωde > -1/3 and ultimately attains a constant value in quintessence region (-1 < ωde < -1/3). The EoS parameter of the model never crosses the phantom divide line (ωde = 1). These facts are consistent with recent observations. We also discuss some other physical parameters.

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