Leavers and remainers: Galaxies split by group-exit
  The disruption of substructure in galaxy clusters likely plays an important
role in shaping the cluster population as a significant fraction of cluster
galaxies today have spent time in a previous host system, and thus may have
been pre-processed. Once inside the cluster, group galaxies face the combined
environmental effects from group and cluster - so called 'post-processing'. We
investigate these concepts, by tracking the evolution of satellites and their
hosts after entering the cluster and find that tidal forces during their first
pericentric passage are very efficient at breaking up groups, preferentially
removing satellites at larger distances from their hosts. 92.2% of satellites
whose host has passed pericentre will leave their host by $z=0$, typically no
later than half a Gyr after pericentric passage. We find satellites leave with
high velocities, and quickly separate to large distances from their hosts,
making their identification within the cluster population challenging. Those
few satellites ($\sim$7.8%) that remain bound to their hosts after a
pericentric passage are typically found close to their host centres. This
implies that substructure seen in clusters today is very likely on first infall
into the cluster, and yet to pass pericentre. This is even more likely if the
substructure is extended, with satellites beyond R$_{200}$ of their host. We
find the cluster dominates the tidal mass loss and destruction of satellites,
and is responsible for rapidly halting the accretion of new satellites onto
hosts once they reach 0.6-0.8 R$_{200}$ radii from the cluster.
