scholarly journals Totally Anisotropic Cosmological Models with Bulk Viscosity for Variable G and Λ

2012 ◽  
Vol 03 (01) ◽  
pp. 9-15 ◽  
Author(s):  
Shri Ram ◽  
Manish K. Singh ◽  
Manoj K. Verma
Keyword(s):  
Bulk Viscosity ◽  
Cosmological Models ◽  
Variable G And Λ ◽  
Anisotropic Cosmological Models ◽  
Variable G

Dark energy and viscous cosmology with variable G and Λ in an anisotropic background

2013 ◽  
Vol 91 (2) ◽  
pp. 153-157 ◽  
Author(s):  
V. Fayaz ◽  
M.R. Setare ◽  
H. Hossienkhani
Keyword(s):  
Dark Energy ◽  
Power Law ◽  
Bulk Viscosity ◽  
Deceleration Parameter ◽  
Chaplygin Gas ◽  
Density Parameter ◽  
Type I ◽  
De Sitter ◽  
Variable G And Λ ◽  
Variable G

The general Bianchi type I with dark energy in the form of standard and modified Chaplygin gas with variable G and Λ and bulk viscosity have been investigated. The de Sitter, power-law and general exponential solutions are assumed for the scale factor in each spatial direction and the corresponding cosmological models are reconstructed. Moreover, for the general exponential solutions, from which the de Sitter and power-law solutions may be obtained, we obtain models that reproduce the early universe, assumed as the inflation, and the late time accelerated expanding universe, that which yields a constant value for the deceleration parameter. We reconstruct bulk viscosity, ξ, gravitational parameter, G, cosmological term, Λ, density parameter, Ω, cosmological constant density parameter, ΩΛ, and deceleration parameter, q, for different equations of state. In the large time limit the model describes an accelerating universe wherein the effective negative pressure induced by Chaplygin gas and bulk viscous pressure are driving the acceleration.

Bulk Viscous Cosmological Models with Variable G and Λ

1998 ◽  
Vol 30 (4) ◽  
pp. 573-581 ◽  
Author(s):  
Tarkeshwar Singh ◽  
A. Beesham ◽  
W. S. Mbokazi
Keyword(s):  
Cosmological Models ◽  
Variable G And Λ ◽  
Bulk Viscous ◽  
Variable G

Causal Viscous Cosmological Models With Variable G and Λ

2000 ◽  
Vol 32 (4) ◽  
pp. 607-614 ◽  
Author(s):  
Tarkeshwar Singh ◽  
A. Beesham
Keyword(s):  
Cosmological Models ◽  
Variable G And Λ ◽  
Variable G

BULK VISCOUS ANISOTROPIC COSMOLOGICAL MODELS WITH VARIABLE G AND Λ

2002 ◽  
Vol 11 (06) ◽  
pp. 893-912 ◽  
Author(s):  
ANIRUDH PRADHAN ◽  
VINOD KUMAR YADAV
Keyword(s):  
Power Law ◽  
Bulk Viscosity ◽  
Bianchi Type ◽  
Einstein Field Equations ◽  
Variable G And Λ ◽  
Field Equations ◽  
Expansion Factor ◽  
Bulk Viscous ◽  
Suitable Power ◽  
Variable G

The Einstein field equations with bulk viscosity and variable G and Λ for Bianchi-type universes are studied under the assumption of a power-law time variation of the expansion factor, achieved via a suitable power-law assumption for the Hubble parameter suggested by M. S. Berman. All the models have a power-law variation of pressure and density and are singular at the epoch t = 0. The variation of G(t) as [Formula: see text] and Λ(t) as [Formula: see text] is consistent with these models.

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