MeerKAT view of Hickson Compact Groups:I. Data description and release

TL;DR

This study uses MeerKAT radio telescope observations to analyze Hickson Compact Groups, revealing extended tidal features and differences between phases, and providing new data on HI gas distribution and galaxy surroundings.

Contribution

First detailed MeerKAT observations of HCGs that improve understanding of gas structures and phase transition in these dense galaxy groups.

Findings

MeerKAT detects more extended tidal features than VLA.

No diffuse HI found in phase 3 groups.

Surrounding galaxies are mostly normal disk galaxies.

Abstract

Context: Hickson Compact Groups (HCGs) are dense gravitationally-bound collections of 4-10 galaxies ideal for studying gas and star formation quenching processes. Aims: We aim to understand the transition of HCGs from possessing complex HI tidal structures (so-called phase 2 groups) to a phase where galaxies have lost most or all their HI (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, integrated spectra, and compared our findings with previous VLA and Green Bank Telescope (GBT) 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 HI 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 disk galaxies. Conclusions: The difference between phase 2 and phase 3 groups is still substantial, supporting previous findings that the transition between the two phases must be abrupt.