Fall 2010 Colloquium Abstracts - James Rhoads

September 1, 2010

A State of the Universe Address (circa 13 billion BC)

James Rhoads (Arizona State University)

Our Universe went through a dramatic transition sometime between its millionth and its billionth birthday, from a blandly uniform distribution of neutral hydrogen and dark matter to an "early modern" universe populated by a diversity of galaxies and black holes, and profoundly influenced by their activity. Several lines of evidence suggest that key events in this transition--- including the first significant galaxies, and the ionization of hydrogen between them--- occurred between 300 and 700 million years after the Big Bang. However, studying the Universe at that epoch requires infrared observations, which present technical challenges imposed by both the Earth's atmosphere and by detector technology. In my talk, I will examine both the physical and observational context for observations in this critical period. I will then summarize our efforts at ASU to push the observational frontier and improve our understanding of early galaxy formation, using a mixture of Arizona telescope resources and NASA's orbiting Great Observatories. I will close with a discussion of future prospects.