Published in Publications of the Astronomical Society of the Pacific, 111: 1475-1502, 1999 December
astro-ph/9912082

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SEARCH TECHNIQUES FOR DISTANT GALAXIES

Daniel Stern and Hyron Spinrad


Department of Astronomy, University of California at Berkeley, Berkeley, CA 94720; dstern@bigz.berkeley.edu, spinrad@bigz.berkeley.edu


Abstract. How and when do galaxies form? Studies of the microwave background radiation reveal that the universe is spectacularly homogenous at redshift z approx 1000. Observations of the local universe reveal that by z = 0 much of the luminous matter has condensed into mature, gravitationally bound structures. One of the primary challenges to astronomers today is to achieve a robust understanding of this process of galaxy formation and evolution. Locating and studying young galaxies at large look-back times is an essential aspect of this program.

We review the systematic observational techniques used to identify galaxies at early cosmic epochs. In the past few years, the study of normal, star-forming galaxies at z > 3 has become possible; indeed, successful methods have been developed to push the frontier past z = 5. We are now directly observing individual galaxies within a Gyr of the big bang. We present a detailed review of the many search methods used for identifying distant galaxies, consider the biases inherent in different search strategies, and discuss early results of these studies. We conclude with goals for future studies at the start of the 21st century.


Table of Contents

INTRODUCTION

HISTORICAL BACKGROUND: BRIGHTEST CLUSTER GALAXIES

SEARCHES AT NON-OPTICAL WAVELENGTHS
High-Redshift Radio Galaxies
Sub-mm Detections of Distant Galaxies
Luminous Infrared Galaxies
X-ray Emission Associated with Distant Galaxies
Gamma-Ray Bursts
Summary

OPTICAL/NEAR-INFRARED SELECTION OF DISTANT GALAXIES
Lyman-Break Galaxies
Photometric Redshifts
Emission Lines Searches for Distant Galaxies
Serendipitous Longslit Searches
Narrow-band Spectroscopy
Targeted Searches
Summary

"PROTOGALAXIES" AT LOW-REDSHIFT

BIASES IN DISTANT GALAXY SEARCH TECHNIQUES

RESULTS: FIRST GLIMPSES TOWARDS THE DARK AGES
Surface Densities of High-Redshift Galaxies
Star Formation Rates and the Cosmic Star Formation History
Effects of the IGM: Hints of the Gunn-Peterson Effect?
Morphology
The Role of Dust
Galaxy Clustering at High Redshift
A Brief Comparison to Theories of Galaxy Formation

CONCLUSIONS AND THOUGHTS FOR THE NEW MILLENNIUM

REFERENCES

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