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Cosmic acceleration with a positive cosmological constant

Arbab I Arbab1

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We have considered a cosmological model with a phenomenological model for the cosmological constant of the form Λ = β R̈/R where β is a constant. For an age parameter consistent with observational data, the universe must be accelerating in the presence of a positive cosmological constant. The minimum age of the universe is H−10, where H0 is the present Hubble constant. The cosmological constant is found to decrease as t−2. Allowing the gravitational constant to change with time leads to an ever-increasing gravitational constant at the present epoch. In the presence of a viscous fluid this decay law for Λ is equivalent to the one with Λ = 3αH2 (α = const) provided α = β/3(β−2). The inflationary solution obtained from this model is that of the de Sitter type.


PACS

98.80.Es Observational cosmology (including Hubble constant, distance scale, cosmological constant, early Universe, etc)

MSC

83F05 Cosmology

Subjects

Gravitation and cosmology

Astrophysics and astroparticles

Dates

Issue 1 (7 January 2003)

Received 19 July 2002

Published 12 December 2002



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