WALLABY Pilot Survey: First Look at the Hydra I Cluster and Ram Pressure
  Stripping of ESO 501-G075
  We present results from neutral atomic hydrogen (HI) observations of Hydra I,
the first cluster observed by the Widefield ASKAP L-band Legacy All-sky Blind
Survey (WALLABY) on the Australian Square Kilometre Array Pathfinder. For the
first time we show that WALLABY can reach its final survey sensitivity.
Leveraging the sensitivity, spatial resolution and wide field of view of
WALLABY, we identify a galaxy, ESO 501-G075, that lies near the virial radius
of Hydra I and displays an HI tail. ESO 501-G075 shows a similar level of
morphological asymmetry as another cluster member, which lies near the cluster
centre and shows signs of experiencing ram pressure. We investigate possible
environmental processes that could be responsible for producing the observed
disturbance in the HI morphology of ESO 501-G075. We rule out tidal
interactions, as ESO 501-G075 has no nearby neighbours within $\sim0.34$Mpc. We
use a simple model to determine that ram pressure can remove gas from the disc
at radii $r\gtrsim25$kpc. We conclude that, as ESO 501-G075 has a typical HI
mass compared to similar galaxies in the field and its morphology is compatible
with a ram pressure scenario, ESO 501-G075 is likely recently infalling into
the cluster and in the early stages of experiencing ram pressure.
