Evidence for Early Filamentary Accretion from the Andromeda Galaxy's Thin Plane of Satellites

Understand

Recently it has been shown that a large fraction of the dwarf satellite galaxies orbiting the Andromeda galaxy are surprisingly aligned in a thin, extended and kinematically coherent planar structure.

• The presence of such a structure seems to challenge the current Cold Dark Matter paradigm of structure formation, which predicts a more uniform distribution of satellites around central objects.
• We show that it is possible to obtain a thin, extended, rotating plane of satellites resembling the one in Andromeda in cosmological collisionless simulations based on the Cold Dark Matter model.
• Our new high resolution simulations show a correlation between the formation time of the dark matter halo and the thickness of the plane of satellites.