Living with lambda

VARUN SAHNI

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

Abstract.

This talk presents a brief overview of recent results pertaining to the cosmological constant L. I summarize the observational situation focussing on observations of high redshift Type Ia supernovae which suggest L> 0. Observations of small angular anisotropies in the cosmic microwave background complement Type Ia supernovae observations and both CMB and Sn can be combined to place strong constraints on the value of L. The presence of a small L-term increases the age of the universe and slows down the formation of large scale structure. I also review recent theoretical attempts to generate a small L-term at the current epoch and a model independent approach for determining the cosmic equation of state.

Keywords: Cosmology; supernovae; cosmic microwave background; cosmological constant; vacuum fluctuations.

Pacs No. 98.80.-k; 98.80.Hw; 98.70.Vc