"Supernovae and the Content of the Universe"
Peter M. Garnavich
Dept. of Physics and Astronomy
Notre Dame University
Abstract
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 that exploded when the Universe was
half its present age, some 7 billion years ago. These distant SNe,
when combined with a local sample analyzed in the same way, give the
surprising result that the Universe appears to be accelerating its
expansion. The acceleration may be the result of a non-zero vacuum
energy but other more exotic forms of energy are possible. Future
supernova searches could help decide the source of the "dark energy"
that dominates the Universe.