The VVV near-IR galaxy catalogue of the southern Galactic disc

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Context. The distribution of galaxies in the zone of avoidance (ZoA) is incomplete due to the presence of our own Galaxy. Aims. Our research is focussed on the identification and characterisation of galaxies in the ZoA, using the new near-infrared (NIR) data from the VVVX survey in regions covering the southern Galactic disc (230° < l < 350°). Methods. We used our previously established procedure, based on photometric and morphological criteria, to identify galaxies. The large data volume collected by the VVVX required alternatives to visual inspection, including artificial intelligence techniques such as classifiers based on neural networks. Results. The VVV NIR galaxy catalogue (VVV NIRGC III) is presented here, covering the southern Galactic disc, significantly extending the vision down to Ks0 = 16 mag throughout the ZoA. This catalogue provides the positions and photometric and morphological parameters for a total of 167 559 galaxies, with their probabilities determined by the CNN and XGBoost algorithms based on image and photometric data, respectively. The construction of the catalogue involves the employment of optimal probability criteria. Finally, 14% of these galaxies were confirmed by visual inspection or by matching with previous catalogues. The peculiarities exhibited by distinct regions across the Galactic disc, along with the characteristics of the galaxies, have been thoroughly examined. The catalogue serves as a valuable resource for extragalactic studies within the ZoA, providing a crucial complement to the forthcoming radio catalogues and future surveys utilising the Vera C. Rubin Observatory and the Nancy Grace Roman Space Telescope. Conclusions. We present a deep galaxy map, covering a 1080 sq. deg. region (230° ≤l ≤ 350° and |b|≤4.5°), which reveals that the apparent galaxy density is predominantly influenced by foreground extinction from the Milky Way. However, the presence of intrinsic inhomogeneities, is also discernible and potentially associated with candidate galaxy groups or clusters and filaments.

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