Identifying Local Group Field Galaxies which have interacted with the
  Milky Way
  We distinguish between Local Group field galaxies which may have passed
through the virial volume of the Milky Way, and those which have not, via a
statistical compari- son against populations of dark matter haloes in the Via
Lactea II (VLII) simulation with known orbital histories. Analysis of VLII
provides expectations for this escaped population: they contribute 13 per cent
of the galactic population between 300 and 1500 kpc from the Milky Way, and
hence we anticipate that about 7 of the 54 known Local Group galaxies in that
distance range are likely to be Milky Way escapees. These objects can be of any
mass below that of the Milky Way, and they are expected to have positive radial
velocities with respect to the Milky Way. Comparison of the radius-velocity
distributions of VLII populations and measurements of Local Group galaxies
presents a strong likelihood that Tucana, Cetus, NGC3109, SextansA, SextansB,
Antlia, NGC6822, Phoenix, LeoT, and NGC185 have passed through the Milky Way.
Most of these dwarfs have a lower HI mass fraction than the majority of dwarfs
lying at similar distances to either the Milky Way or M31. Indeed, several of
these galaxies - especially those with lower masses - contain signatures in
their morphology, star formation history and/or gas content indicative of
evolution seen in simulations of satellite/parent galactic interactions. Our
results offer strong support for scenarios in which dwarfs of different types
form a sequence in morphology and gas content, with evolution along the
sequence being driven by interaction history.
