The Formation of the Local Group Planes of Galaxies

Understand

The confinement of most satellite galaxies in the Local Group to thin planes presents a challenge to the theory of hierarchical galaxy clustering.

• The PAndAS collaboration has identified a particularly thin configuration with kinematic coherence among companions of M31 and there have been long standing claims that the dwarf companions to the Milky Way lie in a plane roughly orthogonal to the disk of our galaxy.
• This discussion investigates the possible origins of four Local Group planes: the plane similar, but not identical to that identified by PAndAS, an adjacent slightly tilted plane, and two planes near the Milky Way: one with nearer galaxies and the other with more distant ones.
• Plausible orbits are found by using a combination of Numerical Action methods and a backward in time integration procedure.