Virgo Filaments VII: MeerKAT HI-imaging of the Virgo III filament

We present MeerKAT H I observations of galaxies in the nearby Virgo iii filament. At a median distance of ~30 Mpc, the filament extends over ≈16 Mpc across ~56 deg2. Our survey comprises 15 targeted MeerKAT pointings centred on H I deficient galaxies. Multi-resolution H I imaging at 8″–90″ with an rms of ~0.3 mJy beam−1 reaches column densities of ~4 × 1020 to ~4 × 1018 atoms cm−2. This probes H I in galaxy discs at ~1.2 kpc resolution and their outskirts at ~13.5 kpc. We detect H I emission from 80 sources within the 500–3000 kms−1 range; most are optically detected galaxies, while 10 per cent lack confirmed counterparts. We also identify three H I clouds without optical counterparts near an interacting system, possibly displaced during the interaction. Galaxies in the filament lie below the field H I gas-fraction scaling relations at fixed stellar mass. Crucially, ~40 per cent of galaxies not selected for H I deficiency fall more than 1σ below these relations, with an even greater fraction lying under the mean relation itself, indicating that the low H I gas fractions are widespread in the filament rather than confined to the pre-selected deficient population. Quantifying H I morphologies using an asymmetry parameter, we find a wide range of disturbances without a clear trend with projected distance to the filament spine or local density, suggesting a combination of local interactions and the filament itself. This paper presents the survey description, catalogue, and H I atlas enabling investigations of gas removal mechanisms in Virgo iii galaxies.