VLA Imaging of H i-bearing Ultra-diffuse Galaxies from the ALFALFA Survey

Abstract

Ultra-diffuse galaxies have generated significant interest due to their large optical extents and low optical surface brightnesses, which challenge galaxy formation models. Here we present resolved synthesis observations of 12 H i -bearing ultra-diffuse galaxies (HUDs) from the Karl G. Jansky Very Large Array, as well as deep optical imaging from the WIYN 3.5 m telescope at Kitt Peak National Observatory. We present the data processing and images, including total intensity H i maps and H i velocity fields. The HUDs show ordered gas distributions and evidence of rotation, important prerequisites for the detailed kinematic models of Mancera Piña et al. We compare the H i and stellar alignment and extent, and find that H i extends beyond the already extended stellar component and the H i disk is often misaligned with respect to the stellar one, emphasizing the importance of caution when approaching inclination measurements for these extreme sources. We explore the H i mass–diameter scaling relation, and find that, although the HUDs have diffuse stellar populations, they fall along the relation with typical global H i surface densities. This resolved sample forms an important basis for more detailed study of the H i distribution in this extreme extragalactic population.