Co-orbiting planes of sub-halos are similarly unlikely around paired and
  isolated hosts
  Sub-halos in dark-matter-based cosmological simulations tend to be
distributed approximately isotropically around their host. The existence of
highly flattened, co-orbiting planes of satellite galaxies has therefore been
identified as a possible problem for these cosmological models, but so far
studies have not considered the hosts' environments. That satellite planes are
now known around both major galaxies in the Local Group raises the question
whether they are more likely around paired hosts. In a first attempt to
investigate this possibility we focus on the flattening and orbital coherence
of the 11 brightest satellite galaxies of the vast polar structure (VPOS)
around the Milky Way (MW). We search for VPOS analogs in the ELVIS suite of
cosmological simulations, which consist of 24 paired and 24 isolated host
halos. We do not find significant differences between the properties of
sub-halo distributions around paired and isolated hosts. The observed
flattening and the observed orbital alignment are each reproduced by only 0.2
to 2 per cent of paired and isolated systems incorporating the obscuration of
satellites by randomly oriented galactic discs. Only one of all 4800 analyzed
realizations (0.02 per cent) reproduces both parameters simultaneously, but the
average orbital pole of this sub-halo system does not align as well with the
normal to the plane fit as observed. That the MW is part of a galaxy pair thus
does not help in explaining the existence of the VPOS if the satellite galaxies
are identified with sub-halos found in dissipationless simulations.
