YZiCS: Preprocessing of dark halos in the hydrodynamic zoom-in simulation of clusters

TL;DR

This study uses high-resolution simulations to analyze how preprocessing in various host environments affects dark matter halos of cluster galaxies, revealing significant tidal stripping and its dependence on host mass and epoch.

Contribution

It provides new insights into the prevalence and impact of preprocessing across different host masses and epochs, emphasizing the role of high-redshift groups in galaxy evolution within clusters.

Findings

Approximately 48% of current cluster members were preprocessed.

Preprocessed fraction is linked to recent cluster mass growth, not cluster mass.

High redshift groups significantly contribute to preprocessing effects.

Abstract

To understand the galaxy population in clusters today, we should also consider the impact of previous environments prior to cluster infall, namely preprocessing. We use YZiCS, a hydrodynamic high-resolution zoom-in simulation of 15 clusters, and focus on the tidal stripping suffered by the dark matter halos of cluster members due to preprocessing. We find ~48% of today's cluster members were once satellites of other hosts. This is slightly higher than previous estimates, in part, because we consider not just group-mass hosts, but hosts of all masses also. Thus, we find the preprocessed fraction is poorly correlated with cluster mass and is instead related to each cluster's recent mass growth rate. Hosts less massive than groups are significant contributors, providing more than one-third of the total preprocessed fraction. We find that halo mass loss is a clear function of the time spent in hosts. However, two factors can increase the mass loss rate considerably; the mass ratio of a satellite to its host, and the cosmological epoch when the satellite was hosted. The latter means we may have previously underestimated the role of high redshift groups. From a sample of heavily tidally stripped members in clusters today, nearly three quarters were previously in a host. Thus, visibly disturbed cluster members are more likely to have experienced preprocessing. Being hosted before cluster infall enables cluster members to experience tidal stripping for extended durations compared to direct cluster infall and at earlier epochs when hosts were more destructive.