  Gaseous outflows are key phenomena in the evolution of galaxies, as they
affect star formation (either positively or negatively), eject gas from the
core or disk, and directly cause mixing of pristine and processed material.
Active outflows may be detected through searches for broad spectral line
emission or high-velocity gas, but it is also possible to determine the
presence of past outflows by searching for extended reservoirs of chemically
enriched molecular gas in the circumgalactic medium (CGM) around galaxies. In
this work, we examine the CO(3-2) emission of a set of seven z~2.0-2.5 AGN host
galaxies, as observed with ALMA. Through a three-dimensional stacking analysis
we find evidence for extended CO emission of radius r~13kpc. We extend this
analysis to the HST/ACS i-band images of the sample galaxies, finding a complex
small-scale (r<10kpc) morphology but no robust evidence for extended emission.
In addition, the dust emission (traced by rest-frame FIR emission) shows no
evidence for significant spatial extension. This indicates that the diffuse CO
emission revealed by ALMA is morphologically distinct from the stellar
component, and thus traces an extended reservoir of enriched gas. The presence
of a diffuse, enriched molecular reservoir around this sample of AGN host
galaxies at cosmic noon hints at a history of AGN-driven outflows that likely
had strong effects on the star formation history of these objects.
