On the origin of tidal features in cluster galaxies

Hosueng Choi (Yonsei University)

Although galaxy mergers are thought to play an important role in forming elliptical galaxies, mergers in galaxy clusters have drawn less attention compared to mergers in field environments due to high peculiar velocities of cluster galaxies. However, comparable fractions of merger features in cluster galaxies have been reported from deep imaging of Abell clusters, suggesting the relevance of mergers in the transformation of cluster early-type galaxies (Sheen et al. 2012). As a more direct approach to understanding the origin of tidal features in clusters, we perform zoomed hydrodynamics simulations on a cluster of galaxies. By utilizing mock observation images of the simulated cluster galaxies, we construct and analyze the cluster early-type galaxy sample in a consistent manner with Sheen et al. 2012. We find ~20% of tidal feature fraction from the simulated cluster, which is comparable to the observational study. Individual evolution history of the galaxies with merger features shows that most of the mergers responsible for the merger features in the present originates from outside the cluster 2Gyrs or further ago. We also find that most of the galaxies with tidal features show correlations with subgroups in the cluster. All these results suggest that merger features in the cluster originates from preprocessing before accretion into the cluster.

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