Physical Society Colloquium

The discovery of a correlation between the light curve shape and intrinsic brightness has made Type Ia supernovae exceptionally accurate distance indicators out to cosmologically interesting redshifts. Ground-based searches and follow-up as well as Hubble Space Telescope observations have been successful in discovering and studying a significant number of Type Ia supernovae with redshifts between 0.3 and 1.0. These distant SNe, when combined with a local sample analyzed in the same way, provide reliable constraints on the deceleration and age of the Universe. Early this year an analysis of a handful of Type Ia events indicated that the deceleration was too small for gravitating matter alone to make a flat Universe. With a larger sample we find the surprising result that the Universe is accelerating and we use the supernovae and cosmic microwave background observations to constrain the properties of the unknown energy that appears to dominate the Universe.

Tuesday, February 2nd 1999, 15:30
Ernest Rutherford Physics Building, room 114