Anomalous gas in ESO 149-G003: A MeerKAT-16 view

Abstract

ESO 149-G003 is a close-by, isolated dwarf irregular galaxy. Previous observations with the ATCA indicated the presence of anomalous neutral hydrogen (H I) deviating from the kinematics of a regularly rotating disc. We conducted follow-up observations with the MeerKAT radio telescope during the 16-dish Early Science programme as well as with the MeerLICHT optical telescope. Our more sensitive radio observations confirm the presence of anomalous gas in ESO 149-G003, and further confirm the formerly tentative detection of an extraplanar H I component in the galaxy. Employing a simple tilted-ring model, in which the kinematics is determined with only four parameters but including morphological asymmetries, we reproduce the galaxy's morphology, which shows a high degree of asymmetry. By comparing our model with the observed H I, we find that in our model, we cannot account for a significant (but not dominant) fraction of the gas. From the differences between our model and the observed data cube, we estimate that at least 7-8 per cent of the H I in the galaxy exhibits anomalous kinematics, while we estimate a minimum mass fraction of less than 1 per cent for the morphologically confirmed extraplanar component.