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

¹ Instituto de Astronomía Teórica y Experimental, (IATE-CONICET), Laprida 854, X5000BGR Córdoba, Argentina
² Observatorio Astronómico de Córdoba, Universidad Nacional de Córdoba, Laprida 854, X5000BGR Córdoba, Argentina
³ Departamento Astronomía, Universidad de La Serena. Av. Raúl Bitran 1305, La Serena, Región de Coquimbo, Chile
⁴ Instituto de Investigación en Astronomía y Ciencias Planetarias, Universidad de Atacama, Copayapu 485, Copiapó, Chile
⁵ Instituto de Altos Estudios Espaciales “Mario Gulich” (CONAE – UNC), Argentina
⁶ Center for Space Science and Technology, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
⁷ Center for Research and Exploration in Space Science and Technology, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
⁸ Instituto de Astrofísica, Depto. de Ciencias Físicas, Facultad de Ciencias Exactas, Universidad Andrés Bello, Av. Fernandez Concha 700, Las Condes, Santiago, Chile
⁹ Vatican Observatory, V00120 Vatican City State, Italy
¹⁰ Max-Planck Institut for Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
¹¹ Centro de Astronomía (CITEVA), Universidad de Antofagasta, Av. Angamos 601, Antofagasta, Chile
¹² Millennium Institute of Astrophysics, Nuncio Monseñor Sotero Sanz 100, Of. 104, Providencia, Santiago, Chile
¹³ Department of Physics & Astronomy, College of Sciences, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA
¹⁴ Instituto de Astronomía y Física del Espacio, CONICET–UBA, Av. Int. Guiraldes 2620, C1428BNB CABA, Argentina
¹⁵ INAF – Osservatorio di Astrofisica e Scienza dello Spazio, via Piero Gobetti 101, I-40129 Bologna, Italy
¹⁶ Departamento de Física, Universidade Federal de Santa Catarina, Trinidade, 88040-900 Florianopolis, Brazil

^⋆ Corresponding author.

Received: 10 September 2024
Accepted: 23 June 2025

Abstract

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 K_s⁰ = 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.