Understand
(Abridged) Using cosmological hydrodynamic simulations in combination with analytic modeling, we show that the galaxy stellar mass-metallicity relation (MZR) provides strong constraints on galactic outflows across cosmic time.
- We compare three outflow models: No outflows, a "constant wind" (cw) model that emulates the popular Dekel & Silk (1986) scenario, and a ``momentum-driven wind" (vzw) model.
- We find that only the vzw scaling reproduces the observed z~2 MZR's slope, amplitude, and scatter.
- Comparing our fully three-dimensional simulations with a simple one-zone chemical evolution model, we find that the MZR can be understood in terms of three parameters: (1) The equilibrium metallicity Z_eq=y*SFR/ACC (where y=true yield), reflecting the enrichment balance between star formation rate SFR and gas accretion rate ACC; (2) the dilution time t_d=M_g/ACC, representing the timescale for a galaxy to return to Z_eq after a metallicity-perturbing interaction; and (3) the blowout mass M_blowout, which is the galaxy stellar mass above which winds can escape its halo.