Hydra I cluster study with H I emission

These WALLABY observations cover a 60-square-degree field of view with uniform sensitivity and a spatial resolution of 30 arcsec. We use these wide-field observations to investigate the effect of galaxy environment on H I gas removal and star formation quenching by comparing the properties of cluster, infall, and field galaxies extending up to ~5R200 from the cluster centre.

We find a sharp decrease in the H I-detected fraction of infalling galaxies at a projected distance of ~1.5*R_200_ from the cluster centre from ~85 per cent to ~35 per cent. We see evidence for the environment removing gas from the outskirts of H I-detected cluster and infall galaxies through the decrease in the H I to r-band optical disc diameter ratio. These galaxies lie on the star-forming main sequence, indicating that gas removal is not yet affecting the inner star-forming discs and is limited to the galaxy outskirts.