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Vol. 53, No. 6
December 1999
pp. 937–944
The cosmological constant revisited
VARUN SAHNI
Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind,
Pune 411 007, India
Abstract.
I briefly review the observational evidence for a small cosmological constant at the present epoch. This evidence mainly comes from high redshift observations of Type 1a supernovae, which, when combined with CMB observations strongly support a flat Universe with øm + øL @ 1. Theoretically a cosmological constant can arise from zero point vacuum fluctuations. In addition ultra-light scalar fields could also give rise to a Universe which is accelerating driven by a time dependent L-term induced by the scalar field potential. Finally a L dominated Universe also finds support from observations of galaxy clustering and the age of the Universe.
Keywords Cosmology; supernovae; cosmic microwave background; cosmological constant; vacuum fluctuations.
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