A comparison of the distribution of satellite galaxies around Andromeda
  and the results of $\Lambda$CDM simulations
  Ibata et al. (2013) recently reported the existence of a vast thin plane of
dwarf galaxies (VTPD) orbiting around Andromeda. We investigate whether such a
configuration can be reproduced within the standard cosmological framework and
search for similar planes of co-rotating satellite galaxies around
Andromeda-like host haloes in data from the Millennium II simulation combined
with a semi-analytic galaxy formation model. We apply a baryonic mass cut of
$2.8\times 10^4 \text{M}_{\text{sun}}$ for the satellite haloes and restrict
the data to a PAndAS like field. If we include the so-called orphan galaxies in
our analysis, we find that planes with a rms lower than the VTPD are common in
Millennium II. This is partially due to the strongly radially concentrated
distribution of orphan galaxies. Excluding part of the orphan galaxies brings
the radial distributions of Millennium II satellites into better agreement with
the satellite distribution of Andromeda while still producing a significant
fraction of planes with a lower rms than the VTPD. We also find haloes in
Millennium II with an equal or higher number of co-rotating satellites than the
VTPD. This demonstrates that the VTPD is not in conflict with the standard
cosmological framework, although a definite answer of this question might
require higher resolution cosmological simulations that do not have to consider
orphan galaxies. Our results finally show that satellite planes in Millennium
II are not stable structures, hence the VTPD might only be a statistical
fluctuation of an underlying more spherical galaxy distribution.
