WALLABY Pilot Survey: the diversity of ram pressure stripping of the
  galactic HI gas in the Hydra Cluster
  This study uses HI image data from the WALLABY pilot survey with the ASKAP
telescope, covering the Hydra cluster out to 2.5$r_{200}$. We present the
projected phase-space distribution of HI-detected galaxies in Hydra, and
identify that nearly two thirds of the galaxies within $1.25r_{200}$ may be in
the early stages of ram pressure stripping. More than half of these may be only
weakly stripped, with the ratio of strippable HI (i.e., where the galactic
restoring force is lower than the ram pressure in the disk) mass fraction (over
total HI mass) distributed uniformly below 90%. Consequently, the HI mass is
expected to decrease by only a few 0.1 dex after the currently strippable
portion of HI in these systems has been stripped. A more detailed look at the
subset of galaxies that are spatially resolved by WALLABY observations shows
that, while it typically takes less than 200 Myr for ram pressure stripping to
remove the currently strippable portion of HI, it may take more than 600 Myr to
significantly change the total HI mass. Our results provide new clues to
understanding the different rates of HI depletion and star formation quenching
in cluster galaxies.
