• The case for the cosmological constant

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      https://www.ias.ac.in/article/fulltext/pram/055/01-02/0043-0052

    • Keywords

       

      Cosmology; supernovae; cosmic microwave background; cosmological constant; vacuum fluctuations

    • 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 Θm ⋍ 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.

    • Author Affiliations

       

      Varun Sahni1

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

       
  • Pramana – Journal of Physics | News

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