Probing the Truncation of Galaxy Dark Matter Halos in High Density Environments from Hydrodynamical N-body Simulations

We analyze high resolution, N-body hydrodynamical simulations of fiducial galaxy clusters to probe tidal stripping of the dark matter subhalos. These simulations include a prescription for star formation allowing us to track the fate of the stellar component as well. We investigate the effect of tidal stripping on cluster galaxies hosted in these dark matter subhalos as a function of projected clustercentric radius. To quantify the extent of the dark matter halos of cluster galaxies, we introduce the half mass radius r1/2 as a diagnostic, and study its evolution with projected cluster-centric distance R as a function of redshift. We find a well defined trend for (r1/2,R) : the closer the galaxies are to the center of the cluster, the smaller the half mass radius. Interestingly, this trend is inferred in all redshift frames examined in this work ranging from z=0 to z=0.7. At z=0, galaxy halos in the central regions of clusters are found to be highly truncated, with the most compact half mass radius of 10 kpc. We also find that r1/2 depends on luminosity and we present scaling relations of r1/2 with galaxy luminosity. The corresponding total mass of the cluster galaxies is also found to increase with projected cluster-centric distance and luminosity, but with more scatter than the (r1/2,R) trend. Comparing the distribution of stellar mass to total mass for cluster galaxies, we find that the dark matter component is preferentially stripped, whereas the stellar component is much less affected by tidal forces. We compare these results with galaxy-galaxy lensing probes of r1/2 and find qualitative agreement. Future surveys with space based telescopes such as dune and snap, that combine wide field and high resolution imaging, will be able to probe the predicted (r1/2,R) relation observationally. Subject headings: galaxies: dark matter halos – numerical simulations: N-body, hydrodynamical