A resolved, multiwavelength study of gas-rich dwarf galaxies in the Fornax cluster using MUSE, MeerKAT, and ALMA

ABSTRACT We combine new and archival Multi-unit spectroscopic explorer (MUSE) observations with data from the MeerKAT Fornax Survey and the ALMA Fornax Cluster Survey to study the ionized, atomic, and molecular gas in six gas-rich dwarf galaxies in the Fornax cluster in detail. We compare the distributions and velocity fields of the three gas phases with each other, with MUSE white-light images, and with the stellar velocity fields. Additionally, we derive the resolved molecular Kennicutt–Schmidt relation for each object, and compare these with existing relations for field galaxies and for the Fornax and Virgo clusters. Finally, we explore global measurements such as gas deficiencies and star formation rates to paint as complete a picture of their evolutionary state as possible. We find that all six gas-rich dwarf galaxies have very disturbed interstellar medium, with all three gas phases being irregular both in terms of spatial distribution and velocity field. Most objects lie well below the Kennicutt–Schmidt relations from the literature. Furthermore, they are quite deficient in H i (with def$_{{\rm{H}{\small I}}}$ between $\sim$1 and $\sim$2 dex), and moderately deficient in H$_2$ (with def$_{\mathrm{ H}_{2}}$ between $\sim$0 and $\sim$1), suggesting that, while both cold gas phases are affected simultaneously, H i is removed in significant quantities before H$_2$. We suggest that these dwarfs are on their first infall into the cluster, and are in the process of transitioning from star-forming to passive. A combination of tidal interactions, mergers/pre-processing, and ram pressure stripping is likely responsible for these transformations.