Tidal stripping as a mechanism for placing globular clusters on wide
  orbits: the case of MGC1 in M31
  The globular clusters of large spiral galaxies can be divided into two
populations: one which formed in-situ and one which comprises clusters tidally
stripped away from other galaxies. In this paper we investigate the
contribution to the outer globular cluster population in the M31 galaxy through
donation of clusters from dwarf galaxies. We test this numerically by comparing
the contribution of globular clusters from simulated encounters to the observed
M31 globular cluster population. To constrain our simulations, we specifically
investigate the outermost globular cluster in the M31 system, MGC1. The remote
location of MGC1 favours the idea of it being captured, however, the cluster is
devoid of features associated with tidal interactions. Hence we separate
simulations where tidal features are present and where they are hidden. We find
that our simulated encounters can place clusters on MGC1-like orbits. In
addition, we find that tidal stripping of clusters from dwarf galaxies leaves
them on orbits having a range of separations, broadly matching those observed
in M31. We find that the specific energies of globular clusters captured by M31
closely matches those of the incoming host dwarf galaxies. Furthermore, in our
simulations we find an equal number of accreted clusters on co-rotating and
counter-rotating orbits within M31 and use this to infer the fraction of
clusters that has been accreted. We find that even close in roughly 50% of the
clusters are accreted, whilst this figure increases to over 80% further out.
