Simulations of the Magellanic Stream in a First Infall Scenario
  Recent high precision proper motions from the Hubble Space Telescope (HST)
suggest that the Large and Small Magellanic Clouds (LMC and SMC, respectively)
are either on their first passage or on an eccentric long period (>6 Gyr) orbit
about the Milky Way (MW). This differs markedly from the canonical picture in
which the Clouds travel on a quasi-periodic orbit about the MW (period of ~2
Gyr). Without a short period orbit about the MW, the origin of the Magellanic
Stream, a young (1-2 Gyr old) coherent stream of HI gas that trails the Clouds
~150 degrees across the sky, can no longer be attributed to stripping by MW
tides and/or ram pressure stripping by MW halo gas. We propose an alternative
formation mechanism in which material is removed by LMC tides acting on the SMC
before the system is accreted by the MW. We demonstrate the feasibility and
generality of this scenario using an N-body/SPH simulation with cosmologically
motivated initial conditions constrained by the observations. Under these
conditions we demonstrate that it is possible to explain the origin of the
Magellanic Stream in a first infall scenario. This picture is generically
applicable to any gas-rich dwarf galaxy pair infalling towards a massive host
or interacting in isolation.
