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

TL;DR

This study combines multi-wavelength observations to analyze gas-rich dwarf galaxies in the Fornax cluster, revealing disturbed interstellar media and gas deficiencies indicative of environmental transformation processes.

Contribution

It provides a detailed, multi-phase gas analysis of dwarf galaxies in a cluster environment, highlighting the impact of cluster interactions on their evolution.

Findings

All six dwarfs have irregular gas distributions and velocity fields.

Most are significantly deficient in HI and moderately in H2.

Dwarfs are likely on their first infall, transitioning from star-forming to passive.

Abstract

We combine new and archival MUSE observations with data from the MeerKAT Fornax Survey and the ALMA Fornax Cluster Survey to study the ionised, 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 ISM, 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 HI (with def_HI between ~1 and ~2 dex), and moderately deficient in H2 (with def_H2 between ~0 and ~1), suggesting that, while both cold gas phases are affected simultaneously, HI is removed in significant quantities before H2. 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.