Annu. Rev. Astron. Astrophys. 1997. 35: 389-443 Copyright © 1997 by Annual Reviews. All rights reserved

Reprinted with kind permission from Annual Reviews, 4139 El Camino Way, Palo Alto, California, USA

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Abstract. The physical properties of the faint blue galaxy population are reviewed in the context of observational progress made via deep spectroscopic surveys and Hubble Space Telescope imaging of field galaxies at various limits and theoretical models for the integrated star formation history of the universe. Notwithstanding uncertainties in the properties of the local population of galaxies, convincing evidence has emerged from several independent studies for a rapid decline in the volume-averaged star-formation rate of field galaxies since a redshift z 1. Together with the small angular sizes and modest mean redshift of the faintest detectable sources, these results can be understood in hierarchical models where the bulk of the star formation occurred at redshifts between z 1-2. The physical processes responsible for the subsequent demise of the faint blue galaxy population remain unclear. Considerable progress will be possible when the evolutionary trends can be monitored in the context of independent physical parameters such as the underlying galactic mass.

Key Words: distant field galaxies, evolution, galaxy formation, cosmology

Table of Contents

• INTRODUCTION
• BASIC METHODOLOGIES
• Predictions in the Absence of Galaxy Evolution
• Evolutionary Predictions
• Images from Hubble Space Telescope
• RECENT OBSERVATIONAL RESULTS
• Number Magnitude Counts
• Faint Redshift Surveys
• Other Probes of Luminosity Evolution
• Imaging Surveys with Hubble Space Telescope
• Evolutionary Constraints from Galaxy Correlation Functions
• ADDRESSING THE MAIN ISSUES
• Uncertainties in the Local Field Galaxy Luminosity Function
• The Role of Low Surface Brightness Galaxies
• Is Number Evolution Required?
• A Distinct Population of Rapidly Fading Objects?
• Evidence for Mergers?
• SURVEYS BEYOND THE SPECTROSCOPIC LIMIT
• Constraints from Gravitational Lensing
• The Hubble Deep Field
• THE STAR-FORMATION HISTORY OF FIELD GALAXIES
• REFERENCES