The Varied Fates of Galaxies in the Young Universe

High-redshift galaxies, observed in the first several billion years after the Big Bang, are thought to be the present-day galaxies at their infancy. Hence, studying the formation and evolution of high-redshift galaxies is key to understanding the history of our own Milky Way as well as of the galaxies in our backyard. Recently, significant progress has been made in characterizing key statistics of high-redshift galaxies; their number densities and spatial clustering as a function of mass and luminosity. However, a more detailed understanding of the star-formation, assembly and chemical histories of the galaxies has been more difficult to obtain. We are still unable to translate these “global” measures into a comprehensive physical picture and to address fundamental questions on the physical processes driving galaxy evolution: What drives star formation? What is the typical star formation history of a galaxy? Do more luminous galaxies have different formation histories from their less-luminous counterparts? Studies that address these questions will elucidate the key physics of galaxy formation; namely, the gas physics that determines the star formation efficiency, and the stellar/black-hole feedback that regulates the star-formation. In this talk, I will review recent progress in our understanding of high-redshift galaxy formation, and discuss observational evidence that strongly suggest that galaxies indeed have very different evolutionary paths within the observed range of parameters.