MeerKAT view of Hickson Compact Groups

I. Data description and release

¹ Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
² Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 43992 Onsala, Sweden
³ Netherlands Institute for Radio Astronomy (ASTRON), Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands
⁴ Steward Observatory, University of Arizona, 933 North Cherry Avenue, Rm. N204, Tucson, AZ 85721-0065, USA
⁵ Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, PR China
⁶ Departament de Física Quàntica i Astrofísica, Universitat de Barcelona, C. Martí i Franquès 1, 08028 Barcelona, Spain
⁷ Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona, C. Martí i Franquès 1, 08028 Barcelona, Spain
⁸ Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
⁹ Department of Physics & Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105, USA
¹⁰ Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
¹¹ Max-Planck-Intitut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
¹² Centre for Radio Astronomy Techniques and Technologies (RATT), Department of Physics and Electronics, Rhodes University, PO Box 94 Makhanda 6140, South Africa
¹³ School of Earth and Space Exploration, Arizona State University, 781 Terrace Mall, Tempe, AZ 85287, USA
¹⁴ Departamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, E-28040 Madrid, Spain
¹⁵ Department of Astronomy, University of Massachusetts, Amherst MA 01003, USA
¹⁶ Department of Astronomy, University of Cape Town, Rondebosch, Cape Town 7700, South Africa
¹⁷ Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 1797, Australia
¹⁸ Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, CAS, Beijing, PR China
¹⁹ National Astronomical Observatories, Chinese Academy of Sciences (NAOC), Beijing, PR China
²⁰ South African Radio Astronomy Observatory, Cape Town 7925, South Africa

^⋆ Corresponding author; ianja@iaa.es

Received: 14 November 2024
Accepted: 3 February 2025

Abstract

Context. Hickson Compact Groups (HCGs) are dense gravitationally bound collections of four to ten galaxies and are ideal for studying gas and star formation quenching processes.

Aims. We aim to understand the transition of HCGs from possessing complex H I tidal structures (so-called phase 2 groups) to a phase where galaxies have lost most or all of their H I (phase 3). We also seek to detect diffuse H I gas that was previously missed by the Very Large Array (VLA).

Methods. We observed three phase 2 and three phase 3 HCGs with MeerKAT and reduced the data using the Containerized Automated Radio Astronomy Calibration (CARACal) pipeline. We produced data cubes, moment maps, and integrated spectra, and we compared our findings with previous VLA and Green Bank Telescope observations.

Results. Compared with previous VLA observations, MeerKAT reveals much more extended tidal features in phase 2 and some new high surface brightness features in phase 3 groups. However, no diffuse H I component was found in phase 3 groups. We also detected many surrounding galaxies for both phase 2 and phase 3 groups, most of which are normal disc galaxies.

Conclusions. The difference between phase 2 and phase 3 groups is still substantial, supporting the previous finding that the transition between the two phases must be abrupt.