HI Galaxy Signatures in the SARAO MeerKAT Galactic Plane Survey -- III. Unveiling the obscured part of the Vela Supercluster

We conducted a search for HI emission of the gas-rich galaxies in the Vela region (260∘ ≤ ≤ 290∘, -2∘ ≤ b ≤ 1∘) to explore the Vela Supercluster (VSCL) at Vₕel ~ 18000 km s⁻¹, largely obscured by Galactic dust. Within the mostly RFI-free band (250 < Vₕel < 25000 km s⁻¹) of MeerKAT, the analysis focuses on $157$ hexagonally distributed pointings extracted from the SARAO MeerKAT Galactic Plane Survey located in the Vela region (Vela$-$SMGPS). These were combined into 10 contiguous mosaics, covering a ~90 deg² area. Among the $843$ HI detected sources, 39 were previously discovered in the Parkes HIZOA survey (Vₕel < 12000 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 HI mass limit reaching log (MHI/ M_) = 9.44 in the VSCL velocity range Vₕel ~ 19500 ± 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 ~ 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 ~ 12000 km s⁻¹. This paper demonstrates the efficiency of systematic HI surveys with the SKA precursor MeerKAT, even in the most obscured part of the Zone of Avoidance (ZOA).