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

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 concludes the decade-long Quasars Probing Quasars survey designed for studying massive galaxy formation and quasar feedback. 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 using a sample of 14 quasar pairs with high-resolution, high S/N spectra. 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 results on kinematics using a sample of 148 quasar pairs with systemic redshifts precisely measured for the foreground quasar-host galaxies. My results suggest the ionization radiation from the quasar is anisotropic or intermittent and the gas is not in inflow.