Breaking the Self-Similarity of Galaxy Formation: A Circumgalactic Medium Perspective
Benjamin Oppenheimer, University of Colorado Boulder
If you could see a dark matter halo directly without knowing the scale, you probably could not distinguish a Milky Way halo from a cluster-sized halo. However, if you look at the galaxies, you would likely see a dominant spiral galaxy in the former and a many quenched and quenching galaxies in the latter. The study of galaxy formation aims to understand how very different galaxies form in dark matter halos of different masses. I will argue for the importance of understanding the gaseous baryons in this context. In contrast to the hot intracluster medium detected in emission in clusters, the circumgalactic medium (CGM) has to be probed by absorption lines toward background quasars and tells a vastly different and complicated story. I will demonstrate, with the aid of hydrodynamic simulations, how the CGM is multi-phase (with cool ~10^4 K clouds embedded in a hot, ambient medium), plus how non-equilibrium ionization processes altering the heavy element ions we probe in spectra. The next frontiers in the CGM require understanding the dynamics encoded not only in absorption line spectra of the UV, but in the X-ray via emission and absorption.
Science with the James Webb Space Telescope
Jane Rigby, NASA/GSFC
NASA’s James Webb Space Telescope (JWST) will have revolutionary capabilities and sensitivity for imaging and spectroscopy from 0.7 to 28 micron. JWST should make major scientific advances across astrophysics, including the physics of reionization, galaxy formation and assembly, planetary science, and extrasolar planets. In anticipation of a scheduled launch in 2019, JWST Cycle 1 Guest Observer proposals will be due in spring of 2018. I will review the scientific capabilities of the telescope, the integration and test program, and how observers will plan observations and analyze JWST data.