A deep Parkes HI survey of the Sculptor group and filament: HI mass function and environment

TL;DR

This study uses the Parkes radio telescope to survey the Sculptor group and filament, revealing 31 HI sources, a flatter HI mass function slope in this environment, and no signs of recent interactions or gas streams.

Contribution

It provides the first detailed HI mass function measurement in the Sculptor filament, highlighting environmental effects on gas content in low-density regions.

Findings

Detected 31 HI sources, including 8 new detections.

Derived a flat HI mass function slope of -1.10.

Found no evidence of extragalactic gas or tidal streams.

Abstract

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.