Aspects of inflation in spatially homogeneous and anisotropic Bianchi Type I spacetime with exponential potential

2018 ◽  
Vol 33 (40) ◽  
pp. 1850238 ◽  
Author(s):  
Raj Bali
Keyword(s):  
Bianchi Type ◽  
Scale Factor ◽  
Type I ◽  
Exponential Potential ◽  
Bianchi Type I ◽  
Inflationary Scenario ◽  
Spatial Volume ◽  
Spatially Homogeneous ◽  
Special Case ◽  
Average Scale Factor

The inflationary scenario in spatially homogeneous and anisotropic Bianchi Type I spacetime with exponential potential [Formula: see text], [Formula: see text] and average scale factor (R) is considered as [Formula: see text] is discussed. The model isotropizes in special case and asymptotically. The spatial volume increases with time representing inflationary scenario and the expansion continues for long enough, thus solving the horizon problem. The model represents decelerating and accelerating phases of universe in special case. Also, the model is singularity free at t = 0. In special case, i.e. when constants b = 0, k = 0, then the model leads to FLRW model for which we have the average scale factor [Formula: see text], [Formula: see text] and deceleration parameter [Formula: see text]. This paper gives the answer why anisotropic and homogeneous Bianchi Type I spacetime is considered than FRW model to discuss inflationary scenario.

Anisotropic models with generalized hybrid expansion in Brans–Dicke theory of gravity

2021 ◽  
pp. 2150141
Author(s):  
S. Surendra Singh ◽  
Yohenba Soibam
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Power Law ◽  
Bianchi Type ◽  
Scale Factor ◽  
Late Time ◽  
Type I ◽  
Coincidence Problem ◽  
Bianchi Type I ◽  
Average Scale Factor

The hybrid expansion law (HEL) for average scale factor that yields power-law and exponential-law cosmologies is considered in spatially homogenous and anisotropic Bianchi type-I model in the context of Brans–Dicke (BD) Theory of gravitation. The solutions of the field equations have been calculated by assuming the power-law expression between the average scale factor [Formula: see text] and scalar field ([Formula: see text]). We studied both interacting and non-interacting forms of dark energy and dark matter and obtained respective solutions. The energy density [Formula: see text] decreases with time while energy densities [Formula: see text] increases with time. In both the cases, the physical acceptability and stability of the models are also studied. The coincidence problem in [Formula: see text]CDM model can be ruled out with proper choice of coupling between dark matter (DM) and dark energy (DE). We also discussed the physical behaviors of the derived models with the current observations applied to late-time acceleration and beginning of the universe. In this model, it is observed that our HEL Bianchi type I universe is highly anisotropic in the beginning of universe and becomes isotropic and overlaps with flat [Formula: see text]CDM model at late times.

CHAOTIC INFLATIONARY SCENARIO IN BIANCHI TYPE I SPACETIME

2012 ◽  
Vol 27 (09) ◽  
pp. 1250049 ◽  
Author(s):  
RAJ BALI
Keyword(s):  
Energy Density ◽  
Bianchi Type ◽  
Type I ◽  
Inflationary Model ◽  
Bianchi Type I ◽  
Inflationary Scenario ◽  
Inflationary Phase ◽  
Chaotic Model ◽  
Frw Model ◽  
Frame Work

Chaotic inflationary model of the early universe proposed by Linde7 is investigated in the frame work of Bianchi type I spacetime. To determine inflationary scenario, we assume that scale factor [Formula: see text], λ being a constant, m the mass, V(ϕ) the potential energy density. It is shown that chaotic model leads to an inflationary phase which also helps in isotropization process. The Higg's field (ϕ) is initially large but decreases due to lapse of time in both cases. The assumption R3 = ABC~e3Ht does not lead to FRW model immediately but for large values of t, it reduces to FRW model since shear σ = 0 in FRW model and shear σ ≠ 0 in Bianchi type I model. The physical aspects of the model are also discussed.

scholarly journals LRS Bianchi type-I cosmological model with constant deceleration parameter in f(R,T) gravity

2017 ◽  
Vol 14 (11) ◽  
pp. 1750158 ◽  
Author(s):  
Binaya K. Bishi ◽  
S. K. J. Pacif ◽  
P. K. Sahoo ◽  
G. P. Singh
Keyword(s):  
Cosmological Model ◽  
Deceleration Parameter ◽  
Hubble Parameter ◽  
Bianchi Type ◽  
Specific Model ◽  
Type I ◽  
Hubble’S Parameter ◽  
Constant Deceleration Parameter ◽  
Bianchi Type I ◽  
Spatially Homogeneous

A spatially homogeneous anisotropic LRS Bianchi type-I cosmological model is studied in [Formula: see text] gravity with a special form of Hubble's parameter, which leads to constant deceleration parameter. The parameters involved in the considered form of Hubble parameter can be tuned to match, our models with the [Formula: see text]CDM model. With the present observed value of the deceleration parameter, we have discussed physical and kinematical properties of a specific model. Moreover, we have discussed the cosmological distances for our model.

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 Invariant Bianchi type I models in f(R,T) gravity

2018 ◽  
Vol 15 (02) ◽  
pp. 1850026 ◽  
Author(s):  
Anil Kumar Yadav ◽  
Ahmad T. Ali
Keyword(s):  
Bianchi Type ◽  
Big Bang ◽  
Type I ◽  
Analysis Method ◽  
Field Equations ◽  
Bianchi Type I ◽  
Nonsingular Solution ◽  
The Big Bang ◽  
Big Bang Singularity ◽  
Special Case

In this paper, we search the existence of invariant solutions of Bianchi type I space-time in the context of [Formula: see text] gravity with special case [Formula: see text]. The exact solution of the Einstein’s field equations are derived by using Lie point symmetry analysis method that yield two models of invariant universe for symmetries [Formula: see text] and [Formula: see text]. The model with symmetries [Formula: see text] begins with big bang singularity while the model with symmetries [Formula: see text] does not favor the big bang singularity. Under this specification, we find out at set of singular and nonsingular solution of Bianchi type I model which present several other physically valid features within the framework of [Formula: see text] gravity.

scholarly journals Spatially Homogeneous and Anisotropic Cosmological Models in Brans-Dicke Theory

1981 ◽  
Vol 34 (3) ◽  
pp. 261 ◽  
Author(s):  
VB Johri ◽  
GK Goswami
Keyword(s):  
Bianchi Type ◽  
Cosmological Models ◽  
Type I ◽  
Bianchi Type I ◽  
Geometrical Properties ◽  
Anisotropic Cosmological Models ◽  
Spatially Homogeneous ◽  
Relativistic Models

Spatially homogeneous and anisotropic cosmological models corresponding to Bianchi type I solutions of Brans-Dicke theory are investigated. The physical and geometrical properties of the models are discussed and compared with the corresponding relativistic models.

scholarly journals Some geometrical aspects of Bianchi type-I space time

2002 ◽  
pp. 79-86
Author(s):  
G. Mohanty ◽  
R.C. Sahu ◽  
P.K. Sahoo
Keyword(s):  
Bianchi Type ◽  
Space Time ◽  
Type I ◽  
Einstein Theory ◽  
Bianchi Type I ◽  
Spatially Homogeneous

A problem of spatially homogeneous Bianchi type-I space-time is investigated in Einstein theory without source of gravitation. Some geometrical natures of the space-time are discussed.

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