Contribution of stripped nuclei to the ultracompact dwarf galaxy
  population in the Virgo Cluster
  We use the hydrodynamical EAGLE simulation to predict the numbers, masses and
radial distributions of tidally stripped galaxy nuclei in massive galaxy
clusters, and compare these results to observations of ultra-compact dwarf
galaxies (UCDs) in the Virgo cluster. We trace the merger trees of galaxies in
massive galaxy clusters back in time and determine the numbers and masses of
stripped nuclei from galaxies disrupted in mergers. The spatial distribution of
stripped nuclei in the simulations is consistent with those of UCDs surrounding
massive galaxies in the Virgo cluster. Additionally, the numbers of stripped
nuclei are consistent with the numbers of M > $10^{7}~M_{\odot}$ UCDs around
individual galaxies and in the Virgo cluster as a whole. The mass distributions
in this mass range are also consistent. We find that the numbers of stripped
nuclei surrounding individual galaxies correlates better with the stellar or
halo mass of individual galaxies than the total cluster mass. We conclude that
most high mass (M > $10^{7}~M_{\odot}$ UCDs are likely stripped nuclei. It is
difficult to draw reliable conclusions about low mass (M < $10^{7}~M_{\odot}$
UCDs because of observational selection effects. We additionally predict that a
few hundred stripped nuclei below a mass of $2~\times~10^{6}~M_{\odot}$ should
exist in massive galaxies that will overlap in mass with the globular cluster
population. Approximately 1-3 stripped nuclei in the process of forming also
exist per massive galaxy.
