Galaxy Zoo: Multi-Mergers and the Millennium Simulation
  We present a catalogue of 39 multiple-mergers found using the mergers
catalogue of the Galaxy Zoo project for $z<0.1$ and compare them to
corresponding semi-analytical galaxies from the Millennium Simulation. We
estimate the (volume-limited) multi-merger fraction of the local Universe using
our sample and find it to be at least two orders of magnitude less than
binary-mergers - in good agreement with the simulations (especially the Munich
group). We then investigate the properties of galaxies in binary- and
multi-mergers (morphologies, colours, stellar masses and environment) and
compare these results with those predicted by the semi-analytical galaxies. We
find that multi-mergers favour galaxies with properties typical of elliptical
morphologies and that this is in qualitative agreement with the models. Studies
of multi-mergers thus provide an independent (and largely corroborating) test
of the Millennium semi-analytical models.
