Compact groups of galaxies in GAMA

We build five considerably large compact group samples, ranging from more than 400 up to roughly 2400 systems, and maximum redshifts from 0.2 to 0.4, depending on the selected parameters. The overall properties of each sample are in agreement with previous findings. Moreover, there is a tendency of compact groups to have a larger fraction of quenched galaxies than control loose groups, mainly for low stellar mass galaxies in compact groups with small crossing times.

In addition, ~45% of compact groups are embedded in loose galaxy systems and display the highest compactness, lowest crossing times and brightest first-ranked galaxies compared to compact groups considered non-embedded or isolated. There is almost no evolution of compact group properties with redshift. Our results confirm previous findings that postulate compact groups as one of the suitable places to study the suppression of the star formation rate in galaxies primarily due to galaxy interactions.

These new Hickson-like compact group samples will be valuable to deepen the analysis of these peculiar galaxy systems in a redshift regime poorly explored so far.