The Geometry and Kinematics of Circumgalactic Gas  [slides]

David Caro building, Level 7 conference room

  • Dr. Nikki Nielsen
    Dr. Nikki Nielsen, Postdoctoral fellow
    Swinburne University

    Email: nikolenielsen[at]


The baryon cycle is key to understanding the observed global properties of galaxies and plays a large part in governing galaxy evolution. Signatures of the baryon cycle such as IGM accretion, minor mergers, and stellar-driven outflows and fountains are best probed in gaseous halos, i.e., the circumgalactic medium (CGM). I use Keck, VLT, and HST spectra of background quasars to examine the geometric and kinematic properties of the multiphase, metal-enriched CGM of galaxies at 0.08<z<1.0, focusing on the low-ionization MgII and high-ionization OVI absorption doublets. By examining the velocity dispersions of absorbers in the context of the host galaxy color and orientation, I find that the low-ionization gas strongly traces expected baryon cycle processes. In contrast, high-ionization gas tends towards broader kinematics independent of galaxy color and orientation. These results suggest that the low- and high-ionization phases may trace different components of the CGM and provide observational constraints on simulations to accurately model the role that the baryon cycle plays in galaxy evolution.

The Geometry and Kinematics of Circumgalactic Gas