scholarly journals Scalar field and time varying cosmological constant in f ( R , T ) gravity for Bianchi type-I universe

2016 ◽  
Vol 54 (2) ◽  
pp. 244-255 ◽  
Author(s):  
G.P. Singh ◽  
Binaya K. Bishi ◽  
P.K. Sahoo
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Bianchi Type ◽  
Type I ◽  
Time Varying ◽  
Bianchi Type I ◽  
Bianchi Type I Universe

scholarly journals Intermediate inflation with non-canonical scalar field in the low anisotropy Universe

2019 ◽  
Vol 34 (33) ◽  
pp. 1950272
Author(s):  
Mahdieh Naderi ◽  
Ali Aghamohammadi ◽  
Abdollah Refaei ◽  
Haidar Sheikhahmadi
Keyword(s):  
Scalar Field ◽  
Bianchi Type ◽  
Type I ◽  
Spectral Indices ◽  
Common Procedure ◽  
Bianchi Type I ◽  
Good Consistency ◽  
Bianchi Type I Universe ◽  
Homogeneous Universe ◽  
Canonical Scalar Field

The behavior of a non-canonical scalar field within an anisotropic Bianchi type I, spatially homogeneous Universe in the framework of the intermediate inflation will be studied. It will be examined on the condition that both the anisotropy and non-canonical sources come together if there is any improvement in compatibility with the observational data originated from Planck 2015. Based on this investigation, it can be observed that automatically a steep potential which can manage inflation in a better way will be obtained. Additionally, as a common procedure for an inflationary study, we shall try to calculate the related inflationary observables such as the amplitude of the scalar perturbations, scalar and tensor spectral indices, tensor-to-scalar ratio, the running spectral index and the number of e-folds. As an exciting part of our results, we will find that our model has a good consistency compared to data resulting from CMB and different Planck results. To justify our claims, the well-known canonical inflationary scenario in an anisotropic Bianchi type I Universe will also be evaluated.

scholarly journals Bianchi Type-I Universe with Cosmological Constant and Quadratic Equation of State inf(R,T)Modified Gravity

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
G. P. Singh ◽  
Binaya K. Bishi
Keyword(s):  
Equation Of State ◽  
Cosmological Constant ◽  
Modified Gravity ◽  
Bianchi Type ◽  
Quadratic Equation ◽  
Type I ◽  
Field Equations ◽  
Bianchi Type I ◽  
Bianchi Type I Universe ◽  
Quadratic Equation Of State

This paper deals with the study of Bianchi type-I universe in the context off(R,T)gravity. Einstein’s field equations inf(R,T)gravity have been solved in the presence of cosmological constantΛand quadratic equation of state (EoS)p=αρ2-ρ, whereα≠0is a constant. Here, we have discussed two classes off(R,T)gravity; that is,f(R,T)=R+2f(T)andf(R,T)=f1(R)+f2(T). A set of models has been taken into consideration based on the plausible relation. Also, we have studied some physical and kinematical properties of the models.

Scalar field solutions for anisotropic universe models in various gravitation theories

2020 ◽  
Vol 17 (02) ◽  
pp. 2050025
Author(s):  
Ali Kabak ◽  
Sezgin Aygün
Keyword(s):  
Scalar Field ◽  
Bianchi Type ◽  
Scalar Potential ◽  
Anisotropic Universe ◽  
Type I ◽  
Bianchi Type I ◽  
Phantom Scalar ◽  
Bianchi Type I Universe ◽  
Phantom Scalar Field ◽  
Universe Models

In this study, we have investigated homogeneous and anisotropic Marder and Bianchi type I universe models filled with normal and phantom scalar field matter distributions with [Formula: see text] in [Formula: see text] gravitation theory (T. Harko et al., Phys. Rev. D 84 (2011) 024020). In this model, [Formula: see text] is the Ricci scalar and [Formula: see text] is the trace of energy–momentum tensor. To obtain exact solutions of modified field equations, we have used anisotropy feature of the universe and different scalar potential models with [Formula: see text] function. Also, we have obtained general relativity (GR) solutions for normal and phantom scalar field matter distributions in Marder and Bianchi type I universes. Additionally, we obtained the same scalar function values by using different scalar field potentials for Marder and Bianchi type I universe models with constant difference in [Formula: see text] gravity and GR theory. From obtained solutions, we get negative cosmological term value for [Formula: see text] constant scalar potential model with Marder and Bianchi type I universes in GR theory. These results agree with the studies of Maeda and Ohta, Aktaş et al. also Biswas and Mazumdar. Finally, we have discussed and compared our results in gravitation theories.

Energy–momentum distributions of Ruban universe in general relativity and teleparallel gravity

2019 ◽  
Vol 34 (03n04) ◽  
pp. 1950011 ◽  
Author(s):  
C. Aktaş
Keyword(s):  
General Relativity ◽  
Bianchi Type ◽  
Teleparallel Gravity ◽  
Type I ◽  
Universe Model ◽  
Zero Energy ◽  
Bianchi Type I ◽  
Momentum Distributions ◽  
Bianchi Type I Universe

In this study, we obtain Einstein, Bergmann–Thomson (BT), Landau–Lifshitz (LL), Møller, Papapetrou (PP) and Tolman energy–momentum (EM) distributions for Ruban universe model in general relativity (GR) and teleparallel gravity (TG). We obtain same results for Einstein, Bergmann–Thomson and Landau–Lifshitz energy–momentum distributions in GR and TG. Also, we get same results for Einstein and Tolman energy–momentum distributions in GR. The Møller energy–momentum results are different in GR and TG. Also, using Ruban universe model, we obtain LRS Bianchi type I solutions and we get zero energy–momentum results for this universe model in GR and TG. These results of LRS Bianchi type I universe model agree with Aygün et al., Taşer et al., Doğru et al., Banerjee–Sen, Tryon and Xulu in different gravitation theories.

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