The Bimodal Absorption System Imaging Campaign
To understand the connection between the galaxy and the circumgalactic medium, I identified and characterized the host galaxies of 19 partial Lyman limit systems at z<1 in Berg et al. (2023). These absorbers (identified in QSO sightlines) were selected based on their HI content only, so I had no a priori knowledge of the gas metallicity or host galaxies. I used integral field spectroscopy observations from VLT/MUSE and Keck/KCWI for this project. There were no strong correlations between the galaxy and gas properties, except for stellar mass. I determined metal-enriched absorbers have a ~78% probability of being associated with galaxies of log(M*) = 9.0 and above, whereas low-metallicity absorbers only have a ~39% probability. From this, we infer 3 absorber populations: a metal-enriched population in the circumgalactic medium of galaxies, a low-metallicity population in the circumgalactic medium of galaxies, and another low-metallicity population associated with overdense regions of the universe.