2021ApJ...922L..29L

The link between the circumgalactic medium (CGM) and the stellar growth of massive galaxies at high-z depends on the properties of the widespread cold molecular gas. As part of the SUPERCOLD-CGM survey (Survey of Protocluster ELANe Revealing CO/[C I] in the Lyα-Detected CGM), we present the radio-loud QSO Q1228+3128 at z = 2.2218, which is embedded in an enormous Lyα nebula. ALMA+ACA observations of CO(4-3) reveal both a massive molecular outflow, and a more extended molecular gas reservoir across ∼100 kpc in the CGM, each containing a mass of M_H2 ∼ 4-5 x 10¹⁰ M_☉. The outflow and molecular CGM are aligned spatially, along the direction of an inner radio jet. After reanalysis of Lyα data of Q1228+3128 from the Keck Cosmic Web Imager, we found that the velocity of the extended CO agrees with the redshift derived from the Lyα nebula and the bulk velocity of the massive outflow. We propose a scenario where the radio source in Q1228+3128 is driving the molecular outflow and perhaps also enriching or cooling the CGM. In addition, we found that the extended CO emission is nearly perpendicular to the extended Lyα nebula spatially, indicating that the two gas phases are not well mixed, and possibly even represent different phenomena (e.g., outflow versus infall). Our results provide crucial evidence in support of predicted baryonic recycling processes that drive the early evolution of massive galaxies.