Anomalous gas in ESO 149-G003: A MeerKAT-16 View
  ESO 149-G003 is a close-by, isolated dwarf irregular galaxy. Previous
observations with the ATCA indicated the presence of anomalous neutral hydrogen
(HI) 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 HI 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 HI, 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% of the HI in the galaxy exhibits
anomalous kinematics, while we estimate a minimum mass fraction of less than 1%
for the morphologically confirmed extraplanar component. We investigate a
number of global scaling relations and find that, besides being gas-dominated
with a neutral gas-to-stellar mass ratio of 1.7, the galaxy does not show any
obvious global peculiarities. Given its isolation, as confirmed by optical
observations, we conclude that the galaxy is likely currently acquiring neutral
gas. It is either re-accreting gas expelled from the galaxy or accreting
pristine intergalactic material.
