Proceedings of IAU 174, "Small Galaxy Groups", Turku, Finland, 13-18 June 1999

Abstract. Interactions between galaxies have spectacular effects on gas dynamics, and small galaxy groups are a privileged place to investigate them. In particular, they could test the existence of cold H₂ gas as dark matter in the outer parts of galaxies. HI observations have revealed that galaxies in small groups are deficient in atomic gas, like in richer galaxy clusters such as Virgo, although in a lesser extent. Galaxy interactions could be the cause of this deficiency, stripping the gas out of galaxies and enriching the inter-cluster medium (ICM) in hot gas, which in turn strips gas through ram pressure. Alternatively, the gas present at the formation of the group could have been heated to its virial temperature, and be observed now as X-rays. The dynamical processes related to this extended gas in small galaxy groups are reviewed.

Key Words: gas, dynamics, dark matter, galaxy interactions

Table of Contents

INTRODUCTION

GAS DYNAMICS IN SMALL GROUPS

Atomic Gas

Molecular Gas

Hot Gas

FORMATION OF GAS CLUMPS

DISCUSSION

REFERENCES