The Role of Interactions and Mergers

Abstract

Galaxy evolution depends strongly on the environment. Dynamical interactions and subsequent evolution make galaxies more concentrated, with higher surface densities, and also trigger star-formation, which consumes the available cold gas. Already at z=0, a large variety of galaxy types are observed, with different evolution stages, from the unevolved gas rich dwarf irregulars, or low surface brightness galaxies, to early-type concentrated galaxies, with no remaining gas. The dynamical processes of galaxy interactions, including internal evolution, are reviewed and evidence is shown of much larger interaction/merging rate at high redshift.