1. Distribution of Merging and Post-merger Galaxies in Nearby Galaxy Clusters
- Author
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Duho Kim, Yun-Kyeong Sheen, Yara L. Jaffé, Kshitija Kelkar, Adarsh Ranjan, Franco Piraino-Cerda, Jacob P. Crossett, Ana Carolina Costa Lourenço, Garreth Martin, Julie B. Nantais, Ricardo Demarco, Ezequiel Treister, and Sukyoung K. Yi
- Subjects
Abell clusters ,Galaxy clusters ,Galaxy mergers ,Interacting galaxies ,Galaxy evolution ,Astrophysics ,QB460-466 - Abstract
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 ≲ z ≲0.08. To this aim, we obtained Dark Energy Camera mosaics in the ${u}^{{\prime} }$ , ${g}^{{\prime} }$ , and ${r}^{{\prime} }$ bands covering up to 3 × R _200 of the clusters, reaching 28 mag arcsec ^−2 surface brightness limits. We visually inspect ${u}^{{\prime} }$ ${g}^{{\prime} }$ ${r}^{{\prime} }$ 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 ∼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.
- Published
- 2024
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