Lucas Kimmig

Satellite Planes around Milky Way Analogues

The Milky Way possesses the best measured plane of satellite galaxies. Using the hydrodynamical cosmological simulation Magneticum Pathfinder, I identified Milky Way analogue that eshibit similar planes of satellites based on the similarity of the planes radial extend and the ratio of the axes of their shape tensors, c/a. About a quarter of all Milky Way mass halos in the simulation actually exhibit satellite planes of similar flatness with c/a < 0.2. However, tracing these disks back in time reveals that most of them are actually only transient in nature, and only in very rare cases it is possible to fine a stable plane persisting over time. In such case, we find indications that these planes are formed through interactions of the satellites after infall, and are not a product of a group-infall or specifically anisotropic infall of the satellites.

Generally, the Milky Way satellites are found to be better aligned than would be expected from an isotropic set of satellites at the same radial distribution, as can be seen on the left, with the latter on average having a c/a = 0.4. For our best Milky Way analogues, we find a similar behaviour, clearly showing that this plane feature is, in fact, a special configuration.