Joint Astrophysics Colloquium

Low-mass, Low-SFR Galaxies at z>2: How the Working Class Are Living

Marcin Sawicki

St. Mary's University

Observational studies of galaxies in the early universe (redshifts z>2) teach us about how present-day galaxies formed and allow us to test theories of cosmic structure formation. To date, such observational efforts have largely been focused on the easier-to-study but relatively rare, luminous objects that form stars at the very high rates of 10s of 100s of solar masses per year. In contrast, their fainter, less active cousins have thus far been largely ignored. But we ignore them at our peril! Although individually faint, these objects are very numerous and so, collectively, are extremely important contributors to the production of stars and heavy chemical elements in the cosmos. Drawing on recent work, I will describe our current understanding of what these numerous, faint objects are, how they differ from their better-studied, luminous cousins, and what they teach us about how structure forms in the universe.