Disassembling the Galaxy with angle-action coordinates

Understand

Angle-action coordinates are used to study the relic of an N-body simulation of a self-gravitating satellite galaxy that was released on a short-period orbit within the disc of the Galaxy.

• Satellite stars that lie within 1.5 kpc of the Sun are confined to a grid of patches in action space.
• As the relic phase-mixes for longer, the patches become smaller and more numerous.
• These patches can be seen even when the angle-action coordinates of an erroneous Galactic potential are used, but using the wrong potential displaces them.