Several scenarios have been suggested to explain the phase-space distribution
of the Milky Way (MW) satellite galaxies in a disc of satellites (DoS). To
quantitatively compare these different possibilities, a new method analysing
angular momentum directions in modelled data is presented. It determines how
likely it is to find sets of angular momenta as concentrated and as close to a
polar orientation as is observed for the MW satellite orbital poles. The method
can be easily applied to orbital pole data from different models. The observed
distribution of satellite orbital poles is compared to published angular
momentum directions of subhalos derived from six cosmological state-of-the-art
simulations in the Aquarius project. This tests the possibility that
filamentary accretion might be able to naturally explain the satellite orbits
within the DoS. For the most likely alignment of main halo and MW disc spin,
the probability to reproduce the MW satellite orbital pole properties turns out
to be less than 0.5 per cent in Aquarius models. Even an isotropic distribution
of angular momenta has a higher likelihood to produce the observed
distribution. The two Via Lactea cosmological simulations give results similar
to the Aquarius simulations. Comparing instead with numerical models of
galaxy-interactions gives a probability of up to 90 per cent for some models to
draw the observed distribution of orbital poles from the angular momenta of
tidal debris. This indicates that the formation as tidal dwarf galaxies in a
single encounter is a viable, if not the only, process to explain the
phase-space distribution of the MW satellite galaxies.Comment: 14 pages, 4 figures, 3 tables. Accepted for publication in MNRA
