Dynamically Produced Moving Groups in Interacting Simulations
  We show that Smoothed Particle Hydrodynamics (SPH) simulations of dwarf
galaxies interacting with a Milky Way-like disk produce moving groups in the
simulated stellar disk. We analyze three different simulations: one that
includes dwarf galaxies that mimic the Large Magellanic Cloud, Small Magellanic
Cloud and the Sagittarius dwarf spheroidal; another with a dwarf galaxy that
orbits nearly in the plane of the Milky Way disk; and a null case that does not
include a dwarf galaxy interaction. We present a new algorithm to find large
moving groups in the $V_R, V_\phi$ plane in an automated fashion that allows us
to compare velocity sub-structure in different simulations, at different
locations, and at different times. We find that there are significantly more
moving groups formed in the interacting simulations than in the isolated
simulation. A number of dwarf galaxies are known to orbit the Milky Way, with
at least one known to have had a close pericenter approach. Our analysis of
simulations here indicates that dwarf galaxies like those orbiting our Galaxy
produce large moving groups in the disk. Our analysis also suggests that some
of the moving groups in the Milky Way may have formed due to dynamical
interactions with perturbing dwarf satellites. The groups identified in the
simulations by our algorithm have similar properties to those found in the
Milky Way, including similar fractions of the total stellar population included
in the groups, as well as similar average velocities and velocity dispersions.
