Quasars Probing Quasars: the Circumgalactic Medium Surrounding z ~ 2 Quasars

Marie Lau (UCSC)
November 3, 2017 - 12:15pm

Abstract

Understanding the gaseous halo surrounding a galaxy is an integral part to understanding galaxy evolution. The z ~ 2 universe is interesting as this is when the star formation rate and AGN activity peak. My work is part of the Quasars Probing Quasars survey designed for studying massive galaxy formation and quasar feedback, which is nearing the end. I use background quasar sightlines that pass close to foreground quasars to study the circumgalactic medium of quasar-host galaxies in absorption. I present results on the statistical and physical properties of the absorbing gas clumps. Compared to coeval star-forming galaxies, the circumgalactic medium surrounding quasars has a larger cool gas mass, is more enriched, and exhibits more extreme kinematics. These results pose challenges for cosmological hydrodynamic simulations. Then I present evidence that the ionizing radiation from the quasar is anisotropic or intermittent and that the circumgalactic gas is not in inflow. Finally, I will discuss other science goals that can be faciliated using spectral databases and absorption-line analysis tools already built.