Galaxy Transformation by Merging

Theoretical considerations and observational data support the idea that mergers were more frequent in the past. At high redshifts, violent interactions and mergers may be implicated in the origin of Lyman-break galaxies, sub-mm starbursts, and active galactic nuclei. Most stars in cluster ellipticals probably formed at redshifts z > 2, as did most of the halo and globular clusters of the Milky Way; these events may all be connected with mergers. But what kind of galaxies merged at high redshifts, and how are these early events connected to present-epoch mergers? I will approach these questions by describing ideas for the formation of the Milky Way, elliptical galaxies, and populations of globular clusters.