ALMA observations of massive molecular gas filaments encasing radio
  bubbles in the Phoenix cluster
  We report new ALMA observations of the CO(3-2) line emission from the
$2.1\pm0.3\times10^{10}\rm\thinspace M_{\odot}$ molecular gas reservoir in the
central galaxy of the Phoenix cluster. The cold molecular gas is fuelling a
vigorous starburst at a rate of $500-800\rm\thinspace M_{\odot}\rm\; yr^{-1}$
and powerful black hole activity in the form of both intense quasar radiation
and radio jets. The radio jets have inflated huge bubbles filled with
relativistic plasma into the hot, X-ray atmospheres surrounding the host
galaxy. The ALMA observations show that extended filaments of molecular gas,
each $10-20\rm\; kpc$ long with a mass of several billion solar masses, are
located along the peripheries of the radio bubbles. The smooth velocity
gradients and narrow line widths along each filament reveal massive, ordered
molecular gas flows around each bubble, which are inconsistent with
gravitational free-fall. The molecular clouds have been lifted directly by the
radio bubbles, or formed via thermal instabilities induced in low entropy gas
lifted in the updraft of the bubbles. These new data provide compelling
evidence for close coupling between the radio bubbles and the cold gas, which
is essential to explain the self-regulation of feedback. The very feedback
mechanism that heats hot atmospheres and suppresses star formation may also
paradoxically stimulate production of the cold gas required to sustain feedback
in massive galaxies.
