YZiCS: On the Mass Segregation of Galaxies in Clusters

TL;DR

This study investigates the presence and mechanisms of mass segregation in galaxy clusters using deep observations and simulations, revealing that mass segregation varies with cluster mass and is influenced by tidal stripping and galaxy infall history.

Contribution

It provides new insights into the dependence of galaxy mass segregation on cluster mass and the role of tidal stripping, supported by both observational data and hydrodynamic simulations.

Findings

Mass segregation is observed more clearly when using the massive galaxy fraction.

The trend of mass segregation is more significant in simulations than in observations.

Galaxies in more massive clusters experience more tidal stripping, affecting mass segregation.

Abstract

Mass segregation, a tendency of more massive galaxies being distributed closer to the cluster center, is naturally expected from dynamical friction, but its presence is still controversial. Using deep optical observations of 14 Abell clusters (KYDISC) and a set of hydrodynamic simulations (YZiCS), we find in some cases a hint of mass segregation inside the virial radius. Segregation is visible more clearly when the massive galaxy fraction is used instead of mean stellar mass. The trend is more significant in the simulations than in the observations. To find out the mechanisms working on mass segregation, we look into the evolution of individual clusters simulated. We find that the degree of mass segregation is different for different clusters: the trend is visible only for low-mass clusters. We compare the masses of galaxies and their dark haloes at the time of infall and at the present epoch to quantify the amount of tidal stripping. We then conclude that satellites that get accreted at earlier epochs or galaxies in more massive clusters go through more tidal stripping. These effects in combination result in a correlation between the host halo mass and the degree of stellar mass segregation.