ALMA unveils widespread molecular gas clumps in the ram pressure
  stripped tail of the Norma jellyfish galaxy
  We present the first high-resolution map of the cold molecular gas
distribution, as traced by CO(2-1) emission with ALMA, in a prominent ram
pressure stripped tail. The Norma cluster galaxy ESO 137-001 is undergoing a
strong interaction with the surrounding intra-cluster medium and is one of the
nearest jellyfish galaxies with a long multi-phase tail. We have mapped the
full extent of the tail at 1" (350 pc) angular resolution and found a rich
distribution of mostly compact CO regions extending to nearly 60 kpc in length
and 25 kpc in width. In total about 10^9 M_sun of molecular gas was detected.
The CO features are found predominantly at the heads of numerous small-scale (~
1.5 kpc) fireballs (i.e., star-forming clouds with linear streams of young
stars extending toward the galaxy) but also of large-scale (~ 8 kpc)
super-fireballs, and double-sided fireballs that have additional diffuse
ionized gas tails extending in the direction opposite to the stellar tails. The
new data help to shed light on the origin of the molecular tail - CO filaments
oriented in the direction of the tail with only diffuse associated Halpha
emission are likely young molecular features formed in situ, whereas other
large CO features tilted with respect to the tail may have originated from the
densest gas complexes that were pushed gradually away from the disk. The ALMA
observations of ESO 137-001, together with observations from HST, Chandra and
VLT/MUSE, offer the most complete view of a spectacular ram pressure stripped
tail to date.
