Distribution of merging and post-merging galaxies in nearby galaxy clusters

We study the incidence and spatial distribution of galaxies that are currently undergoing gravitational merging (M) or that have signs of a post merger (PM) in six galaxy clusters (A754, A2399, A2670, A3558, A3562, and A3716) within the redshift range, 0.05≲z≲0.08. To this aim, we obtained Dark Energy Camera (DECam) mosaics in u^', g^', and r^'-bands covering up to 3× R_200 of the clusters, reaching 28 mag/arcsec^2 surface brightness limits. We visually inspect u^'g^'r^' color-composite images of volume-limited (M_r < -20) cluster-member galaxies to identify whether galaxies are of M or PM types. We find 4 studied. By adding spectroscopic data and studying the projected phase space diagram (PPSD) of the projected clustocentric radius and the line-of-sight velocity, we find that PM-type galaxies are more virialized than M-type galaxies, having 1–5 while the fraction of M-type was ∼10 intermediate environment. Similarly, on a substructure analysis, M types were found in the outskirt groups, while PM types populated groups in ubiquitous regions of the PPSD. Adopting literature-derived dynamical state indicator values, we observed a higher abundance of M types in dynamically relaxed clusters. This finding suggests that galaxies displaying post-merging features within clusters likely merged in low-velocity environments, including cluster outskirts and dynamically relaxed clusters.