COS-EDGES: Co-rotation and kinematic stratification of the multi-phase CGM around edge-on galaxies

We present the first results from the COS-EDGES survey, targeting the kinematic connection between the interstellar medium and multi-phase circumgalactic medium (CGM) in nine isolated, near-edge-on galaxies at, each probed along its major axis by a background quasar at impact parameters of kpc. Using VLT/UVES and HST/COS quasar spectra, we analyse Mgi, Mgii, Hi, Cii, Ciii, and Ovi absorption relative to galaxy rotation curves from Keck/LRIS and Magellan/MagE spectra. We find that low ionisation absorption for 8/9 galaxies lies below the halo escape velocity, indicating bound inflow or recycling gas, while 6/9 galaxies have high ionisation gas reaching above the halo escape velocity, suggesting some unbound material. We find that at lower , over 80% of absorption in all ions lies on the side of systemic velocity matching disk rotation, and the optical-depth-weighted median velocity is consistent with the peak rotation speed. At higher , the kinematics diverge by ionisation state: For the low ionisation gas, the amount of co-rotating absorption remains above 80%, yet drops to roughly 60% of the galaxy rotation speed. For the high ionisation gas (Ovi), only 60% of the absorption is consistent with co-rotation and drops to 20% of the galaxy rotation speed. Furthermore, the velocity widths, corresponding to 50% of the total optical depth for low ionisation gas is up to 1.8 times larger in the inner halo than at larger radii, while for Ciii and Ovi remains unchanged with distance. The 90% optical-depth width shows a modest decline with radius for low ionisation gas but remains constant Ciii and Ovi. At high, both and increase with ionisation potential. These results suggest a radially dependent CGM kinematic structure: the inner halo hosts cool, dynamically broad gas tightly coupled to disk rotation, whereas beyond, particularly traced by Ovi and Hi, the CGM shows weaker rotational alignment and lower relative velocity dispersion. Therefore, low-ionisation gas likely traces extended co-rotating gas, inflows and/or recycled accretion, while high-ionisation gas reflects a mixture of co-rotating, lagging, discrete collisionally ionised structures and volume-filling warm halo, indicating a complex kinematic stratification of the multi-phase CGM.