A Cosmological Model With a Generalized Cosmological Constant

Al-Rawaf, A. S.

doi:10.1142/s0217732398000498

Cited by 28 publications

(15 citation statements)

References 4 publications

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“…Some of the discussions on the cosmological constant problem and consequences on the cosmology with a time-varying cosmological constant have been discussed by Dolgov [29], Sahni and Starobinsky [30], Peebles and Ratra [31], Padmanabhan [32], Vishwakarma [33][34][35], Triay [36] and Kilinc [37], Bertolami [38,39], Chen and Wu [40], Carvalho et al [41], Berman [42,43], Abdel-Rahman [44], Lima and Maia [45]. Al-Rawaf [46] and Overduin and Cooperstock [47] have proposed a cosmological model with a cosmological constant of the form ∝ (R R ). Following the same decay law, Arbab [48] has investigated cosmic acceleration with a positive cosmological constant which is equivalent to ∝ H 2 on dimensional ground.…”

Section: Introductionmentioning

confidence: 99%

Kaluza-Klein Type Cosmological Model of Early Universe with Variable Cosmological Term Λ: Kinematic Tests

Khadekar

Kamdi

2009

Int J Theor Phys

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Kaluza-Klein type cosmological model of universe are consider with variable term in the presence of perfect fluid. We obtained exact solution of the field equations by using gamma law equation of state p = (γ − 1)ρ, in which parameter γ depends on the scale factor R proposed by Carvalho (Int. J. Theor. Phys. 35:2019. A unified description of early universe is presented with the assumption = βH 2 in which inflationary phase is followed by radiation dominated phase. The various physical aspects of the cosmological models are also discussed. Analytic expressions for the look back time, proper distance, luminosity distance and angular diameter distance are derived and their meaning discussed in detail in the framework of higher dimensional space time.

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Section: Introductionmentioning

confidence: 99%

Kaluza-Klein Type Cosmological Model of Early Universe with Variable Cosmological Term Λ: Kinematic Tests

Khadekar

Kamdi

2009

Int J Theor Phys

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“…Carvalho et al (1992), Berman (1990), Waga (1993), Silviera andWaga (1994), andVishwakarma (2000) also investigated cosmological models with a variable cosmological constant by considering a more general Λ term. Al-Rawaf and Taha (1996), Al-Rawaf (1998), Overdin and Cooperstock (1998), and Arbab (2003) investigated cosmological models with a cosmological constant of the form Λ = βR R , where β is a constant. Recently, Khadekar et al (2006) obtained cosmological models assuming the same decay law in higher dimensional RW space-time.…”

Section: Introductionmentioning

confidence: 99%

Bianchi type I two-fluid cosmological models with a variable G and Λ

Oli

2008

Astrophys Space Sci

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This paper presents anisotropic, homogeneous two-fluid cosmological models in a Bianchi type I spacetime with a variable gravitational constant G and cosmological constant Λ. In the two-fluid model, one fluid represents the matter content of the universe and another fluid is chosen to model the CMB radiation. We find a variety of solutions in which the cosmological parameter varies inversely with time t. We also discuss in detail the behavior of associated fluid parameters and kinematical parameters. This paper pictures cosmic history when the radiation and matter content of the universe are in an interactive phase. Here, is closing to 1 throughout the cosmic evolution.

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“…Al-Rawaf and Taha [4], Al-Rawaf [3], Overdin and Cooperstock [22] and Arbab [5,6] investigated cosmological models with the form = βR R , where β is a constant.…”

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confidence: 99%

Viscous Cosmological Model with Variable Gravitational and Cosmological Constants

Singh

2011

Int J Theor Phys

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We have considered some cosmological solutions with variable gravitational and cosmological constants with bulk viscosity. It is found that the solutions are singularity free and the deceleration parameter is in general not a constant unless we assume perfect fluid with equation of state in the standard cosmologies. Moreover, the deceleration parameter is a function of the scale factor and changes sign with evolution, so our solution is a generalization of those obtained by Arbab I. Arbab. The introduction of viscosity not only free from singularity but also give the deceleration parameter a freedom to vary with scale factor. Thus, a viscous cosmological fluid gives a more general situation in the early universe.

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A Cosmological Model With a Generalized Cosmological Constant

Abstract: We suggest a law for the decay of the effective cosmological constant of the form [Formula: see text]. It is shown that this provides more room for consistency with the recent observational data on Hubble's constant and the age of the universe.

Cited by 28 publications

References 4 publications

Kaluza-Klein Type Cosmological Model of Early Universe with Variable Cosmological Term Λ: Kinematic Tests

Kaluza-Klein Type Cosmological Model of Early Universe with Variable Cosmological Term Λ: Kinematic Tests

Bianchi type I two-fluid cosmological models with a variable G and Λ

Viscous Cosmological Model with Variable Gravitational and Cosmological Constants

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