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The case for the cosmological constant

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Abstract

I present a short overview of current observational results and theoretical models for a cosmological constant. The main motivation for invoking a small cosmological constant (or A-term) at the present epoch has to do with observations of high redshift Type Ia supernovae which suggest an accelerating universe. A flat accelerating universe is strongly favoured by combining supernovae observations with observations of CMB anisotropies on degree scales which give the ‘best-fit’ values ΘA ⋍ 0.7 and Θ m ⋍ 0.3. A time dependent cosmological A-term can be generated by scalar field models with exponential and power law potentials. Some of these models can alleviate the ‘fine tuning’ problem which faces the cosmological constant.

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  1. Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, 411 007, Ganeshkhind, Pune, India

    Varun Sahni

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  1. Varun Sahni
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Sahni, V. The case for the cosmological constant. Pramana - J Phys 55, 43–52 (2000). https://doi.org/10.1007/s12043-000-0082-5

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