Invited Review given at the Nobel Symposium, "Particle
Physics and the Universe", Haga Slott, Sweden, August, 1998. Published in
Physica Scripta, Vol. T85, 37-46, 2000
For a PDF version of the article, click
here.
DETERMINATION OF COSMOLOGICAL PARAMETERS
Wendy L. Freedman
Carnegie Observatories,
813 Santa Barbara St., Pasadena, CA 91101
ABSTRACT. Rapid progress has been made
recently toward the measurement of
cosmological parameters. Still, there are areas remaining where future
progress will be relatively slow and difficult, and where further
attention is needed. In this review, the status of measurements of the
matter density
(
m),
the vacuum energy density or cosmological
constant (
), the Hubble constant
(H0), and ages of
the oldest measured objects (t0) are summarized. Many
recent, independent dynamical measurements are yielding a low value for the
matter density
(m ~
0.3). New evidence from type Ia
supernovae suggests that may be non-zero. Many
recent Hubble constant measurements appear to be converging in the
range of 65-75 km/sec/Mpc. Eliminating systematic errors lies at the
heart of accurate measurements for all of these parameters; as a
result, a wide range of cosmological parameter space is currently
still open. Fortunately, the prospects for accurately measuring
cosmological parameters continue to increase and there is good reason
for optimism that success may shortly be forthcoming.
Table of Contents
INTRODUCTION AND BRIEF HISTORICAL OVERVIEW
- DETERMINATION OF m
- DETERMINATION OF
- DETERMINATION OF H0
- Gravitational Lenses
- Sunyaev Zel'dovich Effect and X-Ray
Measurements
- The Extragalactic Distance Scale
- DETERMINATION OF t0
- THE COSMIC MICROWAVE BACKGROUND RADIATION AND
COSMOLOGICAL PARAMETERS
- DISCUSSION AND SUMMARY
- REFERENCES
