Galactic History -- Was the Halo Accreted?

I am part of the "Spaghetti project" (collaborators Dohm-Palmer, Freeman, Harding, Helmi, Mateo, Norris, Olszewski, Shectman) which is searching for kinematic substructure in the Milky Way's halo to answer the question: how much of the Galaxy's halo was accreted from dwarf galaxies like the Sgr dwarf?

The image below, made from models by Paul Harding, shows what a halo might look like which was formed by accretions at various times during the last 10 Gyr of 50 dwarf galaxies.

Here is a higher-resolution version of this plot (2.3M).