Clues to the "Magellanic Galaxy" from Cosmological Simulations
  We use cosmological simulations from the Aquarius Project to study the
orbital history of the Large Magellanic Cloud (LMC) and its potential
association with other satellites of the Milky Way (MW). We search for
dynamical analogs to the LMC and find a subhalo that matches the LMC position
and velocity at either of its two most recent pericentric passages. This
suggests that the LMC is not necessarily on its first approach to the MW,
provided that the virial mass of the Milky Way is M_200 ~1.8e12 M_sun. The
simulation results yield specific predictions for the position and velocity of
systems associated with the LMC prior to infall. If on first approach, most
should lie close to the LMC because the Galactic tidal field has not yet had
enough time to disperse them. If on second approach, the list of potential
associates increases substantially. Interestingly, our analysis rules out an
LMC association for Draco and Ursa Minor, two of the dwarf spheroidals
suggested by Lynden-Bell & Lynden-Bell to form part of the "Magellanic Ghostly
Stream". Our results also indicate that the direction of the orbital angular
momentum is a powerful test of LMC association. This test, however, requires
precise proper motions, which are unavailable for most MW satellites. Of the 4
satellites with published proper motions, only the Small Magellanic Cloud is
clearly associated with the LMC. Taken at face value, the proper motions of
Carina, Fornax and Sculptor rule them out as potential associates, but this
conclusion should be revisited when better data become available. The dearth of
satellites clearly associated with the Clouds might be solved by wide-field
imaging surveys that target its surroundings, a region that may prove a fertile
hunting ground for faint, previously unnoticed MW satellites.
