Presentation #313.02D in the session “Gas in Galaxies”.
The widely-known morphology-density relation provides a direct evidence that the cosmic environment of galaxies influences their constitutional properties and star formation activity. My aim is to obtain a HI perspective on the origin of the morphology density relation. I am investigating the influences of the global and local cosmic environment on the evolution of galaxies, both from the neutral hydrogen (HI) morphologies of galaxies in different locations of cluster substructures and the multi-wavelength (neutral, molecular, ionized gas) case studies of the striking galaxies. Currently, from the MeerKAT telescope observations, I am studying in detail the spatially resolved morphologies and kinematics of the 219 HI detected galaxies in entire volume of Abell 2626 galaxy cluster, covering a range of cosmic environments. At first, I am analysing this data and presenting an atlas with derived data products such as global profiles, HI column density maps and velocity fields, position-velocity diagrams. Then, by identifying the cluster substructures and characterising their environments, I investigate the relative importance and effects of the various physical mechanisms (such as ram pressure stripping (RPS), tidal interaction, harassment etc) that are responsible for reshaping galaxies. I will also study various HI morphologies according to a galaxy’s location in the phase-space diagram in order to trace the gas stripping history of these galaxies as they fall into the cluster. The preliminary analysis shows increase of HI deficient galaxies towards the cluster core, indicating increase of ram-pressure efficiency in the high density cluster core. In addition, I am also looking at the detailed cases of multiphase gas stripping in the “jellyfish galaxies”, the extreme examples of RPS with in-situ star formation in the tails. I have analysed the multi-phase ISM of jellyfish galaxies JW100 and JO204 from multi-wavelength MeerKAT or JVLA, MUSE and ALMA observations and found these galaxies are quite HI deficient with active star formation in the stripped tails and excess amount of molecular gas. Both of these galaxies host AGN, their HI tails are more extended than ionized or molecular gas tails. In both galaxies, the HI emissions are not always co-incident in velocities with the other two gas phases, revealing extremely turbulent ISM of these galaxies. JO204 has associated HI absorption with a redshifted wing towards the central AGN, suggesting RPS is pushing HI gas towards the center, inducing AGN activity in this galaxy.