Galaxy Formation and the Oldest Stellar Systems

点击翻译按钮获取中文摘要

One of the most prominent frontier areas in astrophysics today is to understand the process of galaxy formation and early evolution: how do we uncover the sequence of events that changed the primordial gas emerging from the Big Bang into the distribution of galaxies we see around us today? My research program is directed at investigating the oldest stellar systems in large galaxies: globular star clusters and the oldest halo stars. As the first populations of stars to form during the history of galaxy formation, these systems of old stars give us uniquely detailed observational windows into that critical early era during which star formation and structure formation was the most rapid. ****This kind of work (sometimes referred to as "near-field cosmology") takes advantage of the fact that we can study nearby galaxies in great detail on a star-by-star basis. It is entirely complementary to other types of observational cosmology that search for extremely distant, faint high-redshift galaxies -- where we can see the galaxies directly as they were long ago, but with little or no internal structural detail. The high-redshift surveys tell us the broad-brush features of galaxy formation including their global rates of star formation and their distributions in space; whereas the deep studies of nearby galaxies tell us all the detail about the age distribution of their stars and their chemical enrichment histories. The Objectives in my proposed program are directed at a combination of modelling and observational data analysis of (a) globular clusters, which are the most massive clusters of stars and the remnants of the densest, most massive, and most violent sites of efficient star formation in young galaxies; and (b) the field-halo-star populations in nearby giant galaxies.************