Cosmological gas accretion history onto the stellar discs of Milky Way-like galaxies in the Auriga simulations – (I) Temporal dependency

ABSTRACT We use the 30 simulations of Auriga Project to estimate temporal dependency inflow, outflow, and net accretion rates onto discs Milky Way-like galaxies. The are found be similar for all galaxies at early times, increasing rapidly up $\sim 10~\mathrm{M}_\odot \, \mathrm{yr}^{-1}$. After ∼6 Gyr evolution, however, diverse: in most galaxies, these exhibit an exponential-like decay, but some systems instead present or approximately constant levels time. An exponential fit averaged over MW analogues yields typical decay time-scale 7.2 Gyr. analysis time-evolution inflow outflow rates, their relation star formation rate (SFR) discs, confirms close connection between quantities. First, inflow/outflow ratio stays constant, with values $\dot{M}_\mathrm{out}/ \dot{M}_\mathrm{in} \sim 0.75$, indicating that gas mass involved outflows is order 25 per cent lower compared inflows. A behaviour SFR/inflow ratio, 0.1 0.3, rate/SFR, which varies range 3.5–5.5. Our results show continuous key SFR disc activity subsequent feedback able produce mass-loaded galaxy winds disc–halo interface.