Annu. Rev. Astron. Astrophys. 1997. 35: 357-388
Copyright © 1997 by . All rights reserved


COMPACT GROUPS OF GALAXIES

Paul Hickson

Department of Physics and Astronomy, University of British Columbia,
2219 Main Mall, Vancouver, B.C. V6T1Z4, Canada

email: paul@astro.ubc.ca KEY WORDS: clusters, evolution


ABSTRACT. Compact groups of galaxies have posed a number of challenging questions. Intensive observational and theoretical studies are now providing answers to many of these, and at the same time, are revealing unexpected new clues about the nature and role of these systems. Most compact groups contain a high fraction of galaxies having morphological or kinematical peculiarities, nuclear radio and infrared emission, and starburst or active galactic nuclei (AGN) activity. They contain large quantities of diffuse gas and are dynamically dominated by dark matter. They most likely form as subsystems within looser associations and evolve by gravitational processes. Strong galaxy interactions result and merging is expected to lead to the ultimate demise of the group. Compact groups are surprisingly numerous, and may play a significant role in galaxy evolution.


Table of Contents

INTRODUCTION

IDENTIFICATION AND SURVEYS

SPACE DISTRIBUTION AND ENVIRONMENT

DYNAMICAL PROPERTIES

STRUCTURE AND MORPHOLOGY

Shapes and Orientations
Compact Group Galaxies
Optical Luminosity Function
Star Formation and Nuclear Activity
Diffuse Light
Cool Gas
Hot Gas

PHYSICAL NATURE

Discordant Redshifts
Physical Association and Density

COSMOLOGICAL IMPLICATIONS

Clustering and Large-Scale Structure
Galaxy Evolution and Merging
Role in Galaxy Formation and Evolution
Gravitational Lensing
Cosmology

REFERENCES

For a postscript version of the article, click here.

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