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

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

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FAINT BLUE GALAXIES

Richard Ellis


Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, England; e-mail: rse@ast.cam.ac.uk


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 approx 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 approx 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

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