Measuring Inflows, Outflows, and Rotation in the Hot Circumgalactic Medium of Nearby Simulated Disk Galaxies with LEM

The circumgalactic medium (CGM) is the multiphase gas surrounding galaxies and is the reservoir from which gas flows onto galaxies and into which stellar and active galactic nuclei feedback eventually deposit mass, momentum, and energy. The dominant portion of the CGM by mass is hot and emits in X-rays. The Line Emission Mapper (LEM) probe is an X-ray observatory that would have the capability to map the thermodynamic, chemical, and kinematic properties of the CGM. In this work, we analyze the velocity fields of the hot X-ray emitting CGM of two Milky Way-mass disk galaxies from the TNG50 simulation using synthetic LEM observations. These are characterized by inflows and outflows in directions perpendicular to the disk, as well as rotation of the CGM which is generally aligned with the rotation of the stellar disk. We investigate the properties of the X-ray line shapes which will be produced by CGM motions, which will be determined by the types of velocity fields in the CGM as well as the observed line of sight. We also determine the relationship between the velocity fields of the cold and hot gas components of the galaxies, and how this relationship could be probed with multi-wavelength observations. Our results show how X-rays can detect and analyze the flows of hot gas into and out of the CGM that drive the formation and ongoing evolution of galaxies.