Abstract

The exchange of baryons between galaxies and their surrounding intergalactic medium (IGM) is a crucial but poorly constrained aspect of galaxy formation and evolution. I will present results from the Keck Baryonic Structure Survey (KBSS) and the Cosmic Ultraviolet Baryon Survey (CUBS), two spectroscopic surveys designed to explore the evolution of galaxies and their surrounding intergalactic and circumgalactic baryons during the height of cosmic star formation and its decline to present day. Analysis of KBSS and CUBS QSO sightline data constrain the thermodynamics, kinematics, and chemistry of the CGM over the majority of the Universe’s history and four decades of galaxy luminosity, providing direct constraints on gas flows in and out of galaxies. I will highlight results on the size, kinematics, and thermal properties of circumgalactic gas at z~2 and the multi-elemental chemical abundances of the intermediate redshift CGM. Collectively, these data demonstrate the CGM provides one of the best testing grounds for models of galaxy-scale outflows. I’ll conclude by briefly discussing new observations, including a large HST and cycle 1 JWST program which will further elucidate the connection between galaxies and their surrounding gas across cosmic time, as well as a new instrument, Magellan/MIRMOS, being built at Carnegie which will provide unprecedented constraints on the kinematics of gas within the CGM.