H i galaxy signatures in the SARAO MeerKAT galactic plane survey − III. Unveiling the obscured part of the Vela Supercluster

We conducted a search for H\, I emission of the gas-rich galaxies in the Vela region (260° ≤ ℓ ≤ 290°, −2° ≤ b ≤ 1°) to explore the Vela Supercluster (VSCL) at Vhel ∼ 18 000 km\, s⁻¹, largely obscured by Galactic dust. Within the mostly Radio Frequency Interference-free band (250 < Vhel < 25 000 km\, s⁻¹) of MeerKAT, the analysis focuses on 157 hexagonally distributed pointings extracted from the South African Radio Astronomy Observatory MeerKAT Galactic Plane Survey located in the Vela region (Vela−SMGPS). These were combined into 10 contiguous mosaics, covering an ∼90 square degrees area. Among the 843 H\, I detected sources, 39 were previously discovered in the H i Parkes Zone of Avoidance survey (Vhel < 12 000 km\, s⁻¹; rms ∼ 6 mJy\, beam⁻¹). With the improved rms level of the Vela−SMGPS, i.e. 0.29–0.56 mJy\, beam⁻¹, our study unveils nearly 12 times more detections (471 candidates) in that same velocity range. We furthermore could identify 187 galaxy candidates with an H\, I mass limit reaching log (MHI/ M) = 9.44 in the VSCL velocity range Vhel ∼ 19 500 ± 3500 km\, s⁻¹. We find indications of two wall-like overdensities that confirm the original suspicion that these walls intersect at low latitudes around longitudes of ℓ ∼ 272°–278°. We also find a strong signature most likely associated with the Hydra/Antlia extension and evidence of a previously unknown narrow filament at Vhel ∼ 12 000 km\, s⁻¹. This paper demonstrates the efficiency of systematic H\, I surveys with the Square Kilometre Array (SKA) precursor MeerKAT, even in the most obscured part of the Zone of Avoidance.