Gas accretion and galactic fountain flows in the Auriga cosmological simulations: angular momentum and metal re-distribution

Understand

Using a set of 15 high-resolution magnetohydrodynamic cosmological simulations of Milky Way formation, we investigate the origin of the baryonic material found in stars at redshift zero.

• We find that roughly half of this material originates from subhalo/satellite systems and half is smoothly accreted from the Inter-Galactic Medium (IGM).
• About $90 \%$ of all material has been ejected and re-accreted in galactic winds at least once.
• The vast majority of smoothly accreted gas enters into a galactic fountain that extends to a median galactocentric distance of $\sim 20$ kpc with a median recycling timescale of $\sim 500$ Myr.