Does the dwarf galaxy system of the Milky Way originate from Andromeda?

Understand

The Local Group is often seen to be a quiescent environment without significant merger events.

• However an ancient major merger may have occurred in the most massive galaxy.
• Numerical simulations have shown that tidal tails formed during gas-rich major mergers are long-lived and could be responsible for old stellar streams and likely induce the formation of tidal dwarf galaxies (TDGs).
• Using several hydrodynamical simulations we have investigated the most prominent tidal tail formed during the first passage, which is gas-rich and contains old and metal poor stars.