Distribution of Merging and Post-merger Galaxies in Nearby Galaxy Clusters
ASTROPHYSICAL JOURNAL(2024)
摘要
We study the incidence and spatial distribution of galaxies that are currently undergoing gravitational merging (M) or that have signs of being post-merger (PM) in six galaxy clusters (A754, A2399, A2670, A3558, A3562, and A3716) within the redshift range of 0.05 less than or similar to z less than or similar to 0.08. To this aim, we obtained Dark Energy Camera mosaics in the u ' , g ' , and r ' bands covering up to 3 x 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 type. We find 4% M-type and 7% PM-type galaxies in the galaxy clusters 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 a 1%-5% higher fraction within the escape-velocity region, while the fraction of M-type was similar to 10% higher than the PM type in the intermediate environment. Similarly, on a substructure analysis, M types were found in groups in the outskirts, while PM-type populated groups were found 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-merger features within clusters likely merged in low-velocity environments, including clusters outskirts and dynamically relaxed clusters.
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关键词
Abell clusters,Galaxy clusters,Galaxy mergers,Interacting galaxies,Galaxy evolution
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