| 17th of May 2021 |
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| WALLABY observations of the Hydra I cluster |
| by Reynolds et al. |
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Reynolds et al. present results from neutral atomic hydrogen (HI)
observations of the Hydra I cluster taken as part of the Widefield
ASKAP L-band Legacy All-sky Blind Survey (WALLABY). The Hydra I
cluster is located ~60 Mpc (about 200 million light years) away and
contains 581 optically detected galaxies. Reynolds et al. find
that 51 galaxies are detected in HI emission within the cluster. Of
the 51, five galaxies are found to be large enough (i.e., sufficiently
spatially resolved) to allow detailed kinematic and mass model
analysis. Reynolds et al. consider in detail one of these, ESO
501−G075, that lies near the edge of the cluster and displays an HI
tail directed away from the cluster centre. They conclude that, ESO
501−G075 is likely recently infalling into the cluster and in the
early stages of experiencing ram pressure.
The image shows a Digitized Sky Survey (DSS) grey-scale image of the Hydra I cluster with the 51 ASKAP detections shown by the blue/red contours. The 5 galaxies with red contours are those that are well spatially resolved: ESO 501−G075 is at the centre of the orange dot-dashed circle. The black star and dashed circle indicate the centre and virial radius of the Hydra I cluster. The diagonal grey line in the lower left corner is an artefact in the DSS image. The large HI contour to the lower right is an interacting galaxy group. |