Nonlinear spinor field in Bianchi type-I cosmology: Inflation, isotropization, and late time acceleration

2006 ◽  
Vol 74 (12) ◽  
Author(s):  
Bijan Saha
Keyword(s):  
Spinor Field ◽  
Bianchi Type ◽  
Late Time ◽  
Type I ◽  
Nonlinear Spinor ◽  
Bianchi Type I ◽  
Late Time Acceleration

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.

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.

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.

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