The extended HI halo of NGC 4945 as seen by MeerKAT
  Observations of the neutral atomic hydrogen (HI) in the nuclear starburst
galaxy NGC 4945 with MeerKAT are presented. We find a large amount of halo gas,
previously missed by HI observations, accounting for 6.8% of the total HI mass.
This is most likely gas blown into the halo by star formation. Our maps go down
to a $3\sigma$ column density level of $5\times10^{18} cm^{-2}$ . We model the
HI distribution using tilted-ring fitting techniques and find a warp on the
galaxy's approaching and receding sides. The HI in the northern side of the
galaxy appears to be suppressed. This may be the result of ionisation by the
starburst activity in the galaxy, as suggested by a previous study. The origin
of the warp is unclear but could be due to past interactions or ram pressure
stripping. Broad, asymmetric HI absorption lines extending beyond the HI
emission velocity channels are present towards the nuclear region of NGC 4945.
Such broad lines suggest the existence of a nuclear ring moving at a high
circular velocity. This is supported by the clear rotation patterns in the HI
absorption velocity field. The asymmetry of the absorption spectra can be
caused by outflows or inflows of gas in the nuclear region of NGC 4945. The
continuum map shows small extensions on both sides of the galaxy's major axis
that might be signs of outflows resulting from the starburst activity.
