M31 Merger Tidal-Tail Origin of the Milky Way Vast Polar Structure
A test of whether the Milky Way's Vast Polar Structure (VPOS) of co-orbiting dwarf satellite galaxies originated from a recent major merger at Andromeda (M31). Using Gaia DR3 proper motions, the study traces VPOS dwarf orbits back one billion years in 6D phase space and compares them with tidal-tail particles predicted by M31 merger simulations, finding that for low-mass Milky Way models most VPOS dwarfs -- including the Large Magellanic Cloud and its associated dwarfs -- coincide with the infalling tidal tail once ram-pressure slowing by the Milky Way corona is accounted for. It proposes the VPOS formed from a baryonic matter exchange between M31 and the Milky Way.
Astronomy & Astrophysics manuscript no. aa52131-24_rev5 ©ESO 2025 February 18, 2025 An intriguing
This astrophysics paper investigates the origin of the Milky Way's Vast Polar Structure (VPOS) -- the roughly perpendicular plane in which about twenty of the Milky Way's dwarf satellite galaxies co-…