AN LRS BIANCHI TYPE-I COSMOLOGICAL MODEL WITH TIME-DEPENDENT Λ TERM

2007 ◽  
Vol 16 (04) ◽  
pp. 745-754 ◽  
Author(s):  
J. P. SINGH ◽  
R. K. TIWARI
Keyword(s):  
Cosmological Model ◽  
Bianchi Type ◽  
Large Fraction ◽  
Cosmological Term ◽  
Type I ◽  
De Sitter ◽  
Stiff Matter ◽  
Bianchi Type I ◽  
Rotationally Symmetric ◽  
De Sitter Universe

In this paper, we investigate locally rotationally symmetric (LRS) Bianchi type-I cosmological model containing stiff matter with a cosmological term proportional to the Hubble parameter. This variation law for vacuum density has recently been proposed by Schützhold on the basis of quantum field estimations in the curved and expanding background. The model obtained approaches isotropy. The cosmological term tends asymptotically to a genuine cosmological constant and the model tends to a de Sitter universe. We obtain that the present universe is accelerating with a large fraction of cosmological density in the form of cosmological term. Taking matter density equal to half of the vacuum density, as suggested by observation, we obtain a universe age given by Ht = 0.55 and a decelerating parameter equal to 2σ2/3H2.

scholarly journals Locally Rotationally Symmetric Bianchi Type-I Cosmological Model in f(R,T) Gravity

2019 ◽  
Vol 1344 ◽  
pp. 012004
Author(s):  
M.Vijaya Santhi ◽  
Daba Meshesha Gusu ◽  
V.U.M. Rao ◽  
G. Suryanarayana
Keyword(s):  
Cosmological Model ◽  
Bianchi Type ◽  
Type I ◽  
Bianchi Type I ◽  
Locally Rotationally Symmetric ◽  
Rotationally Symmetric

scholarly journals Viscous Bianchi Type I Universe with Stiff Matter and Decaying Vacuum Energy Density

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Raj Bali ◽  
Pratibha Singh ◽  
J. P. Singh
Keyword(s):  
Bulk Viscosity ◽  
Bianchi Type ◽  
Cosmological Term ◽  
Vacuum Energy Density ◽  
Late Time ◽  
Type I ◽  
Stiff Matter ◽  
Bianchi Type I ◽  
Initial Epoch ◽  
Bianchi Type I Universe

We examine homogeneous and anisotropic Bianchi type I cosmological model with viscous stiff matter and time-varying cosmological term which scales with Hubble parameter H. The resulting model approaches isotropy. The cosmological term relaxes to a genuine cosmological constant, and the model in the absence of bulk viscosity tends to a deSitter universe asymptotically. Our scenario presents an initial epoch with decelerating expansion followed by late-time acceleration consistent with observations. Bulk viscosity advances the accelerating phase in the model and prevents the matter density to vanish for large times.

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.

NON-COMMUTATIVE BIANCHI QUANTUM COSMOLOGY

2007 ◽  
Vol 16 (10) ◽  
pp. 1625-1632 ◽  
Author(s):  
W. GUZMÁN ◽  
C. ORTIZ ◽  
M. SABIDO ◽  
J. SOCORRO ◽  
MAXIMO A. AGÜERO
Keyword(s):  
Cosmological Model ◽  
Probability Density ◽  
Quantum Cosmology ◽  
Bianchi Type ◽  
Cosmological Term ◽  
Type I ◽  
Bianchi Type I ◽  
The Universe ◽  
Arbitrary Factor

Introducing non-commutative variables in the minisuperspace, we obtain the non-commutative quantum solutions to the Wheeler–DeWitt equation with an arbitrary factor ordering, for the anisotropic Bianchi type I cosmological model, coupled to barotropic matter and cosmological term Λ. From the probability density, the inclusion of non-commutativity seems to retard the isotropization of the universe.

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.

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