???????Constraints on galactic outflows from the metallicity-stellar mass-SFR relation of EAGLE simulation and SDSS galaxies

Stellar feedback-dri ven outflo ws regulate the stellar formation and chemical enrichment of galaxies, yet the underlying dependence of mass outflow rate on galaxy properties remains largely unknown. We develop a simple yet comprehensive non-equilibrium chemical evolution model (NE-CEM) to constrain the mass-loading factor eta of outflows using the metallicitystellar mass-SFR relation observed by Sloan Digital Sky Survey (SDSS) at z = 0. Our NE-CEM predicts the chemical enrichment by explicitly tracking both the histories of star formation and mass-loading. After exploring the EAGLE simulation, we disco v er a compact yet flexible model that accurately describes the average star formation histories of galaxies. Applying a novel method of chemically measuring eta to EAGLE , we find eta can be parametrized by its dependence on stellar mass and specific SFR as log eta proportional to M(*)(alpha)sSFR(beta), with alpha= -0.12 and beta=0.32 in EAGLE . Our chemically inferred eta agrees remarkably well with the kinematic measurements by Mitchell et al. After e xtensiv e tests with EAGLE , we apply an NE-CEM Bayesian analysis to the SDSS data, yielding a tight constraint of log (eta/0.631) = 0 . 731 +/- 0 . 002 x ( M-*/109. 5 M-circle dot)(-0.222 +/- 0.004)(sSFR / 10 (-9.5) yr (-1))(0.078 +/- 0.003), in good agreement with the down-the-barrel measurements. Our best-fitting NE-CEM not only accurately describes the metallicitystellar mass-SFR relation at z = 0, but also successfully reproduce the so-called "fundamental metallicity relation' at higher redshifts. Our results reveal that different galaxies form stars and enrich their gas in a non-equilibrium but strikingly coherent fashion across cosmic time.