Contribution of stripped nuclear clusters to globular cluster and
  ultra-compact dwarf galaxy populations
  We use the Millennium II cosmological simulation combined with the
semi-analytic galaxy formation model of Guo et al. (2011) to predict the
contribution of galactic nuclei formed by the tidal stripping of nucleated
dwarf galaxies to globular cluster (GC) and ultra-compact dwarf galaxy (UCD)
populations of galaxies. We follow the merger trees of galaxies in clusters
back in time and determine the absolute number and stellar masses of disrupted
galaxies. We assume that at all times nuclei have a distribution in
nucleus-to-galaxy mass and nucleation fraction of galaxies similar to that
observed in the present day universe. Our results show stripped nuclei follow a
mass function $N(M) \sim M^{-1.5}$ in the mass range $10^6 < M/M_\odot < 10^8$,
significantly flatter than found for globular clusters. The contribution of
stripped nuclei will therefore be most important among high-mass GCs and UCDs.
For the Milky Way we predict between 1 and 3 star clusters more massive than
$10^5 M_\odot$ come from tidally disrupted dwarf galaxies, with the most
massive cluster formed having a typical mass of a few times $10^6 M_\odot$,
like omega Centauri. For a galaxy cluster with a mass $7 \times 10^{13}
M_\odot$, similar to Fornax, we predict $\sim$19 UCDs more massive than
$2\times10^6 M_\odot$ and $\sim$9 UCDs more massive than $10^7 M_\odot$ within
a projected distance of 300 kpc come from tidally stripped dwarf galaxies. The
observed number of UCDs are $\sim$200 and 23, respectively. We conclude that
most UCDs in galaxy clusters are probably simply the high mass end of the GC
mass function.
