Massive molecular outflow and 100 kpc extended cold halo gas in the
  enormous Ly$\alpha$ nebula of QSO 1228+3128
  The link between the circum-galactic 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/\ci\ in the Ly$\alpha$-Detected CGM), we present the
radio-loud QSO Q1228+3128 at $z=2.2218$, which is embedded in an enormous
Ly$\alpha$ nebula. ALMA+ACA observations of CO(4-3) reveal both a massive
molecular outflow, and a more extended molecular gas reservoir across $\sim$100
kpc in the CGM each containing a mass of M$_{\rm
H2}$\,$\sim$\,4$-$5\,$\times$\,10$^{10}$ M$_{\odot}$. The outflow and molecular
CGM are aligned spatially, along the direction of an inner radio jet. After
re-analysis of Ly$\alpha$ 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 Ly$\alpha$ 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
Ly$\alpha$ nebula spatially, indicating that the two gas phases are not well
mixed, and possibly even represent different phenomena (e.g., outflow vs.
infall). Our results provide crucial evidence in support of predicted baryonic
recycling processes that drive the early evolution of massive galaxies.
