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.

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.

Transit dark energy string cosmological models with perfect fluid in F(R,T)-gravity

2018 ◽  
Vol 15 (10) ◽  
pp. 1850168 ◽  
Author(s):  
Rashid Zia ◽  
Dinesh Chandra Maurya ◽  
Anirudh Pradhan
Keyword(s):  
Dark Energy ◽  
Early Time ◽  
Momentum Tensor ◽  
Late Time ◽  
Field Equations ◽  
Accelerating Expansion ◽  
Type Ia ◽  
Dynamical Parameters ◽  
The Stability ◽  
The Universe

In this paper, spatially homogeneous and anisotropic Bianchi type-[Formula: see text] dark energy (DE) cosmological transit models with string fluid source in [Formula: see text] gravity [T. Harko et al., Phys. Rev. D 84 (2011) 024020], where [Formula: see text] is the Ricci scalar and [Formula: see text] the trace of the stress energy–momentum tensor, have been studied in the context of early time decelerating and late-time accelerating expansion of the Universe as suggested by the recent observations. The exact solutions of the field equations are obtained first by using generalized hybrid expansion law (HEL) [Formula: see text] which yields a time-dependent deceleration parameter [Formula: see text] and second by considering the metric coefficient [Formula: see text]. By using recent constraints from supernovae type-Ia union data [Cunha, arXiv:0811.2379[astro-ph]], we obtain [Formula: see text] and [Formula: see text] for transit model [Formula: see text]. The Universe has an initial singularity and is anisotropic closed and it tends to be flat at the late time, i.e. our Universe is in accelerating expansion. Our model shows a phase transition property from decelerating to accelerating. It is remarkable to mention here that our Universe is homogeneous and anisotropic in the early phase whereas it becomes homogeneous and isotropic for [Formula: see text]. We have also discussed the stability of the background solution with respect to perturbations of the metric along with the properties of future singularities in the Universe dominated by DE including the phantom-type fluid. Various physical and dynamical parameters are also calculated and investigated in terms of time and redshift both.

BULK VISCOUS BIANCHI TYPE I BAROTROPIC FLUID COSMOLOGICAL MODEL WITH VARYING Λ AND FUNCTIONAL RELATION ON HUBBLE PARAMETER IN ROSEN’S BIMETRIC GRAVITY

2021 ◽  
Vol 10 (5) ◽  
pp. 2515-2525
Author(s):  
N.P. Gaikwad ◽  
P.V. Lepse ◽  
B.K. Bishi ◽  
N.K. Ashtankar
Keyword(s):  
Cosmological Model ◽  
Hubble Parameter ◽  
Bianchi Type ◽  
Functional Relation ◽  
Late Time ◽  
Type I ◽  
Bianchi Type I ◽  
Barotropic Fluid ◽  
Bimetric Gravity ◽  
Bulk Viscous

We have deduced that bulk viscous Bianchi type I barotropic fluid cosmological model with varying $\Lambda$ and functional relation on hubble parameter by solving the field equations bimetric theory of gravitation. It is observed that our model has exponentially accelerating expansion at late time starting with decelerating expansion which agreed the observation of Perlmutter (1998), Knop (2003), Tegmark (2004) and Spergel (2006). In the beginning, our model has more than three spatial-dimensions then it switched over to three-dimensional spatial geometry at late epoch of time and it is agreed with Borkar et al. (2013). Other geometrical and physical behavior of the model have been studied.

On a Bianchi type-I space-time with bulk viscosity in f(R,T) gravity

2021 ◽  
Author(s):  
M. Koussour ◽  
M. Bennai
Keyword(s):  
Deceleration Parameter ◽  
Bianchi Type ◽  
Momentum Tensor ◽  
Energy Conditions ◽  
Type I ◽  
Field Equations ◽  
Bulk Fluid ◽  
Bianchi Type I ◽  
Deceleration Phase ◽  
Spatially Homogeneous

In this paper, we present a spatially homogeneous and anisotropic Bianchi type-I cosmological model with a viscous bulk fluid in [Formula: see text] gravity where [Formula: see text] and [Formula: see text] are the Ricci scalar and trace of the energy-momentum tensor, respectively. The field equations are solved explicitly using the hybrid law of the scale factor, which is related to the average Hubble parameter and gives a time-varying deceleration parameter (DP). We found the deceleration parameter describing two phases in the universe, the early deceleration phase [Formula: see text] and the current acceleration phase [Formula: see text]. We have calculated some physical and geometric properties and their graphs, whether in terms of time or redshift. Note that for our model, the bulk viscous pressure [Formula: see text] is negative and the energy density [Formula: see text] is positive. The energy conditions and the [Formula: see text] analysis for our spatially homogeneous and anisotropic Bianchi type-I model are also discussed.

scholarly journals LRS Bianchi type-I Universe with anisotropic dark energy and special form of deceleration parameter in f (R, T) gravity

2018 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
Rajesh Wankhade ◽  
A.S. Bansod
Keyword(s):  
Deceleration Parameter ◽  
Special Form ◽  
Bianchi Type ◽  
Momentum Tensor ◽  
Physical Aspect ◽  
Type I ◽  
Field Equations ◽  
Bianchi Type I ◽  
Anisotropic Dark Energy ◽  
Bianchi Type I Universe

In this paper, LRS Bianchi type-I space-time is considered in the presence of perfect fluid source in the frame work of  gravity (Harko et al. in Phys.Rev. D 84:024020, 2011) where is an arbitrary function of Ricci scalar  and trace of the energy momentum tensor . The Einstein’s field equations have been solved by taking into account the special form of deceleration parameter (Singha A., Debnath U.: Int.J. Theor. Phys.48, 2009). We observe that in f (R, T) gravity, an extra acceleration is always present due to coupling between matter and geometry. The geometrical and physical aspect of the model is also studied.

scholarly journals Approximate Solutions of the LRS Bianchi Type-I Cosmological Model

Symmetry ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 403
Author(s):  
Yihu Feng ◽  
Lei Hou
Keyword(s):  
Cosmological Model ◽  
Homotopy Perturbation Method ◽  
Bianchi Type ◽  
Approximate Solutions ◽  
Space Time ◽  
Type I ◽  
Main Field ◽  
Field Equations ◽  
Bianchi Type I ◽  
Homotopy Perturbation

In this current study, we explore the modified homogeneous cosmological model in the background of LRS Bianchi type-I space–time. For this purpose, we employ the Homotopy Perturbation Method (HPM). HPM is an analytical-based method. Further, we calculated the main field equations of the cosmological model LRS Bianchi type-I space–time. Furthermore, we discuss the necessary calculations of HPM. Therefore, we investigate the analytical solution of our problem by adopting HPM. In this response, we discuss five different values of parameter n. We also give a brief discussion about solutions. The main purpose of this study is to apply the application of HPM in the cosmological field.

scholarly journals Bianchi Type I Cosmological Models with Expansion Driven by Particle Creation

2018 ◽  
Author(s):  
Kalyani Desikan
Keyword(s):  
Bianchi Type ◽  
Energy Momentum Tensor ◽  
Particle Creation ◽  
Momentum Tensor ◽  
Conservation Equation ◽  
Type I ◽  
Field Equations ◽  
Bianchi Type I ◽  
Energy Conservation Equation ◽  
The Universe

A study of Bianchi Type I cosmological model is undertaken in the framework of creation of particles. To accommodate the creation of new particles, the universe is regarded as an Open thermodynamical system. The energy conservation equation is modified with the incorporation of a creation pressure in the energy momentum tensor. Exact solutions of the field equations are obtained (i) for a particular choice of the particle creation function and (ii) by considering the deceleration parameter to be constant. In the first model the behavior of the solution at late times is investigated. The physical aspects of the model have also been discussed. In the case of the second model we have restricted our analysis to the power law behaviour for the average scale factor. This leads to a particular form for the particle creation function. The behavior of the solution is investigated and the physical aspects of the model have also been discussed for the matter dominated era.

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.

Quadratically varying deceleration parameter in f(R,T) gravity

2020 ◽  
Vol 17 (10) ◽  
pp. 2030003
Author(s):  
Rishi Kumar Tiwari ◽  
Değer Sofuoğlu
Keyword(s):  
Deceleration Parameter ◽  
Early Time ◽  
Big Bang ◽  
Momentum Tensor ◽  
Late Time ◽  
Type I ◽  
Linearly Varying Deceleration Parameter ◽  
Dynamical Parameters ◽  
Acceleration Of The Universe ◽  
New Form

In this paper, we have proposed a new form for the varying deceleration parameter that is a generalization of the form of Ö. Akarsu and T. Dereli [Cosmological models with linearly varying deceleration parameter, Int. J. Theor. Phys. 51(2012) 612]. LRS Bianchi type-I cosmological model filled with a 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 using this new form of time-varying deceleration parameter. The time evolution of physical and dynamical parameters have been analyzed and shown by graphs. Moreover, the deceleration parameter has been considered in terms of redshift. It has been shown that the model starts with a big bang and ends with a big rip. It is filled by a quintessence like fluid at the early time and by a phantom like fluid at the late time.

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.

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