Institution(s): 1. University of Edinburgh
Hierarchical theories of structure formation predict an abundance of dynamical fossils in the integral-of-motion space of the Milky Way, a prediction that Gaia will put to a test. However, the existence of a `smooth' stellar halo poses an intriguing question: how can a featureless halo component arise from the merger of smaller bodies?
In this talk I will show that the construction of dynamical invariants, i.e. quantities that are conserved throughout the motion of stars, provide an ideal methodology for studying the evolution of unbound substructures in a time-dependent potential. I will also show that a `smooth' stellar halo is an inescapable by-product of the hierarchical growth of galaxies.