A deep Parkes HI survey of the Sculptor group and filament: HI mass
  function and environment
  We present the results of a deep survey of the nearby Sculptor group and the
associated Sculptor filament taken with the Parkes 64-m radio telescope in the
21-cm emission line of neutral hydrogen. We detect 31 HI sources in the
Sculptor group/filament, eight of which are new HI detections. We derive a
slope of the HI mass function along the Sculptor filament of $\alpha =
-1.10^{+0.20}_{-0.11}$, which is significantly flatter than the global mass
function and consistent with the flat slopes previously found in other
low-density group environments. Some physical process, such as star formation,
photoionisation or ram-pressure stripping, must therefore be responsible for
removing neutral gas predominantly from low-mass galaxies. All of our HI
detections have a confirmed or tentative optical counterpart and are likely
associated with luminous rather than 'dark' galaxies. Despite a column density
sensitivity of about $4 \times 10^{17}~\mathrm{cm}^{-2}$, we do not find any
traces of extragalactic gas or tidal streams, suggesting that the Sculptor
filament is, at the current time, a relatively quiescent environment that has
not seen any recent major interactions or mergers.
