scholarly journals Some Robertson-Walker Models with Variable G and λ

1997 ◽  
Vol 50 (5) ◽  
pp. 893 ◽  
Author(s):  
Abdussattar ◽  
R. G. Vishwakarma
Keyword(s):  
Fluid Flow ◽  
Cosmological Parameters ◽  
Time Varying ◽  
Variable G And Λ ◽  
Flow Vector ◽  
Ricci Collineation ◽  
Frw Models ◽  
Variable G

Some Robertson-Walker (RW) models admitting a contracted Ricci collineation along the fluid flow vector and having time-varying G and Λ are investigated. The nature of the expansion of the models obtained in the cases k = ±l is found to be interchanged from the corresponding standard FRW models. Estimates of the present values of various cosmological parameters are obtained and found to be well within the observational limits.

scholarly journals Higher derivative corrections of f(R) gravity with varying equation of state in the case of variable G and Λ

2015 ◽  
Vol 93 (4) ◽  
pp. 449-455 ◽  
Author(s):  
M. Khurshudyan ◽  
B. Pourhassan ◽  
A. Pasqua
Keyword(s):  
Numerical Analysis ◽  
Equation Of State ◽  
Modified Gravity ◽  
Deceleration Parameter ◽  
Cosmological Parameters ◽  
Variable G And Λ ◽  
Hubble Expansion ◽  
Higher Derivative ◽  
Higher Order Terms ◽  
Variable G

In this paper, we study three models of f(R) modified gravity including higher order terms based on different equation of state parameters. We also assume variable G and Λ. Using numerical analysis, we obtain the behavior of some important cosmological parameters, like the Hubble expansion H parameter and the deceleration parameter q. Statefinder diagnostics are also performed for all models.

Some FRW models with variable G and

1997 ◽  
Vol 14 (4) ◽  
pp. 945-953 ◽  
Author(s):  
Abdussattar ◽  
R G Vishwakarma
Keyword(s):  
Frw Models ◽  
Variable G

Decelerating to accelerating FRW universe with variable G and Λ in conharmonically flat space

New Astronomy ◽  
2019 ◽  
Vol 66 ◽  
pp. 79-87 ◽  
Author(s):  
Manish Goyal ◽  
Rishi Kumar Tiwari ◽  
Anirudh Pradhan
Keyword(s):  
Flat Space ◽  
Variable G And Λ ◽  
Frw Universe ◽  
Variable G

scholarly journals FRW Cosmology with Variable G and Λ

2011 ◽  
Vol 50 (5) ◽  
pp. 1602-1613 ◽  
Author(s):  
Mubasher Jamil ◽  
Ujjal Debnath
Keyword(s):  
Frw Cosmology ◽  
Variable G And Λ ◽  
Variable G
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