Figuring Out Gas & Galaxies in Enzo (FOGGIE). XV. Examining the Spatial and Kinematic Relationship between Circumgalactic Mg ii and O vi

Understanding the thermodynamic properties of the circumgalactic medium (CGM) is key to uncovering the baryon cycle in galaxies. Here, we present spatial and kinematic relationships between Mg ii and O vi , as representatives for low- and high-ion-bearing gas, in the cosmological zoom-in galaxy simulation suite FOGGIE, a set of Milky Way–like galaxy simulations with high CGM resolution. We find the O vi -bearing gas exists as a diffuse halo around the Galactic disk, while the Mg ii -bearing gas is more centrally located. We investigate the covering fraction, probability of co-observation, and cokinematic correspondence of these ions using two different analysis methods. We make both mock sightlines using two-dimensional projections of our simulations, treating these cells as integrated lines of sight, and we create one-dimensional ray objects and use the Synthetic Absorption Line Surveyor Application code to investigate individual gas structures that contribute most to the line-of-sight column densities, which we call mock absorbers. We explore the relative kinematics of these mock absorbers and find Mg ii and O vi appear to have a cokinematic relationship when looking at absorber pairs with the closest relative velocity, like in J. K. Werk et al. However, this does not necessarily correspond to a close spatial separation, meaning many O vi and Mg ii absorber pairs only appear to be cokinematic but are physically unrelated. Taking a more holistic look at Mg ii and O vi absorber pairs reveals a much weaker correlation between these two ions.