Monday

Galaxies can be accreted by clusters either individually, or in galaxy groups, which typically contain tens of members. A group environment can strongly affect the properties of its member galaxies, and similarly, large galaxy clusters affect the properties of both infalling groups and of the galaxies in these groups. Cosmological simulations are an important tool in understanding these structures; they allow us to study the full histories of galaxies and groups being accreted by a cluster. Using data from The Three Hundred project, a large suite of hydrodynamical simulations of galaxy clusters, we examine how groups evolve as they fall into a cluster. We show that a cluster impacts the dynamics of infalling groups differently as groups approach the cluster, and as they pass through it. By studying the journeys of galaxies in these infalling groups, we can constrain which galaxies were previously bound to a group, but have since been stripped from it. This allows us to determine observable differences between groups that are approaching a cluster for the first time, and those that have been nearby to a cluster for a longer period. We also investigate the prevalence of galaxy mergers in infalling groups and the connection between backsplash galaxies and groups, both of which depend on the dynamical properties of their host group. With our analysis, we are able to more deeply understand the past physical processes that result in the cluster substructure that we observe today.