COS-SAGA: A 3-sightline Probe of a Local Group Analog’s CGM

The flow of gas into and out of galaxies is crucial to understanding how galaxies quench. However, the connection between the circumgalactic medium (CGM) and satellite galaxies is poorly understood. In this poster, I will describe the COS-SAGA survey, targeting quasars around local (d < 40 Mpc ) Milky Way-like galaxies with known satellites population from the Satellites Around Galactic Analogs survey (SAGA, Geha et al. 2017, Mao et al. 2021). In this poster we describe a particular system from COS-SAGA that has 3 different sightlines, as well as a single satellite, leading to simpler interpretation then more complex or less data-rich systems. We describe both the observations themselves, as well as a modeling approach to mapping theoretical histories of the system to the QSO observations. This system thus serves as both a fascinating data point in its own right and as a test case for future missions like HWO that will blow the door open on understanding the CGM and its connection both to host galaxies and their attendant satellites.