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 Ω m + ΩA ⋍ 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 Λ-term induced by the scalar field potential. Finally a Λ dominated Universe also finds support from observations of galaxy clustering and the age of the Universe.
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Sahni, V. The cosmological constant revisited. Pramana - J Phys 53, 937–944 (1999). https://doi.org/10.1007/s12043-999-0048-1
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DOI: https://doi.org/10.1007/s12043-999-0048-1