Massive molecular gas reservoir around the central AGN in the CARLA
  J1103+3449 cluster at z=1.44
  Passive early-type galaxies dominate cluster cores at z $\lesssim$1.5. At
higher redshift, cluster core galaxies are observed to have still on-going
star-formation, fuelled by cold molecular gas. We measure the molecular gas
reservoir of the central region around the radio-loud AGN in the cluster CARLA
J1103+3449 at z=1.44 with NOEMA. The AGN synchrotron emission dominates the
continuum emission at 94.48 GHz, and we measure its flux at the AGN position
and at the position of two radio jets. Combining our measurements with
published results over the range 4.71 GHz-94.5 GHz, we obtain a flat spectral
index $\alpha = 0.14 \pm 0.03$ for the AGN core emission, and a steeper index
$\alpha = 1.43 \pm 0.04$ and $\alpha = 1.15 \pm 0.04$ at positions close to the
western and eastern lobe, respectively. The total spectral index is $\alpha =
0.92 \pm 0.02$ over the range 73.8 MHz-94.5 GHz. We detect two CO(2-1) emission
lines, both blue-shifted with respect to the AGN. Their emission corresponds to
two regions, ~17 kpc south-east and ~14 kpc south-west of the AGN, not
associated with galaxies. In these two regions, we find a total massive
molecular gas reservoir of $M_{gas}$ = 3.9 $\pm$ 0.4 $10^{10} M_{\odot}$, which
dominates (~ 60%) the central total molecular gas reservoir. These results can
be explained by massive cool gas flows in the center of the cluster. The AGN
early-type host is not yet quenched; its star formation rate is consistent with
being on the main sequence of star-forming galaxies in the field (SFR~30-140
$M_{\odot}$/yr), and the cluster core molecular gas reservoir is expected to
feed the AGN and the host star-formation before quiescence. The other cluster
confirmed members show star formation rates at ~2 $\sigma$ below the field main
sequence at similar redshifts and do not have molecular gas masses larger than
galaxies of similar stellar mass in the field.
