Resolved HI in two ultra-diffuse galaxies from contrasting non-cluster environments

Authors: T. C. Scott, Chandreyee Sengupta, P. Lagos, Aeree Chung, O. Ivy Wong

Monthly Notices of the Royal Astronomical Society

We report on the first resolved HI observations of two blue ultra-diffuse galaxies (UDGs) using the Giant Metrewave Radio Telescope (GMRT). These observations add to the so-far limited number of UDGs with resolved HI data. The targets are from contrasting non-cluster environments: UDG-B1 is projected in the outskirts of Hickson Compact Group 25 and Secco-dI-2 (SdI-2) is an isolated UDG. These UDGs also have contrasting effective radii with R_e of 3.7kpc (similar to the Milky Way) and 1.3kpc respectively. SdI-2 has an unusually large MHIM∗MHIM∗ ratio =28.9, confirming a previous single dish HI observation. Both galaxies display HI morphological and kinematic signatures consistent with a recent tidal interaction, which is also supported by observations from other wavelengths, including optical spectroscopy. Within the limits of the observations' resolution our analysis indicates that SdI-2 is dark matter-dominated within its HI radius and this is also likely to be the case for UDG-B1.Our study highlights the importance of high spatial and spectral resolution HI observations for the study of the dark matter properties of UDGs.

https://ui.adsabs.harvard.edu/abs/2021MNRAS.tmp..419S/abstract