Applying Liouville's Theorem to Gaia Data

Understand

The Milky Way is filled with the tidally-disrupted remnants of globular clusters and dwarf galaxies.

• Determining the properties of these objects -- in particular, initial masses and density profiles -- is relevant to both astronomy and dark matter physics.
• However, most direct measures of mass cannot be applied to tidal debris, as the systems of interest are no longer in equilibrium.
• Since phase-space density is conserved during adiabatic phase mixing, Liouville's theorem provides a connection between stellar kinematics as measured by observatories such as Gaia and the original mass of the disrupted system.