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THE HUBBLE CONSTANT
Wendy L. Freedman & Barry F. Madore
Carnegie Observatories, 813 Santa Barbara St.,
Pasadena, CA 91101, USA
Abstract: Considerable progress has been made in determining the
Hubble constant
over the past two decades. We discuss the cosmological context and
importance of an accurate measurement of the Hubble constant, and
focus on six high-precision distance-determination methods: Cepheids,
tip of the red giant branch, maser galaxies, surface-brightnes
fluctuations, the Tully-Fisher relation and Type Ia supernovae. We
discuss in detail known systematic errors in the measurement of galaxy
distances and how to minimize them. Our best current estimate of the
Hubble constant is 73 ± 2 (random) ± 4
(systematic) km s-1 Mpc-1. The importance of improved
accuracy in the Hubble constant will increase over the next decade
with new missions and experiments designed to increase the precision
in other cosmological parameters. We outline the steps that will be
required to deliver a value of the Hubble constant to 2% systematic
uncertainty and discuss the constraints on other cosmological
parameters that will then be possible with such accuracy.
Key words : Cosmology, Distance Scale, Cepheids,
Supernovae, Age of Universe
Table of Contents
INTRODUCTION
- EXPANSION OF THE UNIVERSE: THE COSMOLOGICAL
CONTEXT
- MEASUREMENT OF DISTANCES
- Cepheid Distance Scale
- Tip of the Red Giant Branch (TRGB) Method
- Maser Galaxies
- Surface Brightness Fluctuation (SBF) Method
- Tully-Fisher Relation
- Type Ia Supernovae
- THE HUBBLE SPACE TELESCOPE (HST) KEY PROJECT
- Systematics on Ho at the
End of the Key Project and a Decade Later
- OTHER METHODS FOR DETERMINING Ho
- Gravitational Lens Time Delays and
Ho
- The Sunyaev-Zel'dovich (SZ) Effect and
Ho
- Measurements of Anisotropies in the Cosmic
Microwave Background
- AGE OF THE UNIVERSE
- WHY MEASURE Ho TO HIGHER ACCURACY?
- Constraints on Dark Energy
- Constraints on the Neutrino Mass
- Measuring Ho to ± 2%
- FUTURE IMPROVEMENTS
- SUMMARY POINTS
- DISCLOSURE STATEMENT
- REFERENCES
