The Physics department colloquia are usually on Friday afternoons at 3:30 pm in Lapham Hall Room 160. Coffee and cookies are served at 3:15 pm in the same room. Anyone is welcome.

The Cyclying of Baryons Between Stars and Circumgalactic Space
Dr. Hsiao-Wen Chen, Dept. of Astronomy & Astrophysics, Kevli Institute for Cosmological Physics, The University of Chicago

Tremendous progress has been made over the last decade in our empirical and theoretical understanding of how galaxies form and evolve across cosmic time. In particular, state-of-the-art cosmological simulations can not only match the large-scale statistical properties of galaxies, but they can also successfully reproduce the observed small-scale features such as star and gas surface density profiles, and specific angular momentum.

This success shows that the basic theoretical framework for modeling galaxy formation is on the right track. However, there is a growing recognition that these models have fallen short in matching the empirical properties of diffuse gas, which constitutes 90% of all baryons in the universe, beyond visible galaxy disks and into circumgalactic space. An accurate understanding and characterization of the complex physical processes that govern the interactions between star-forming regions and this diffuse circumgalactic medium (CGM) is the next frontier in extragalactic research.

I will highlight some of the observational efforts of my group at the University of Chicago to identify the dominant mechanisms which define the CGM properties.