The metallicity of galactic winds

Abstract

The abundance evolution of galaxies depends critically on the balance between the mixing of metals in their interstellar medium, the inflow of new gas and the outflow of enriched gas. We study these processes in gas columns perpendicular to a galactic disk using sub-parsec resolution simulations that track stellar ejecta with the Flash code. We model a simplified interstellar medium stirred and enriched by supernovae and their progenitors. We vary the density distribution of the gas column and integrate our results over an exponential disk to predict wind and ISM enrichment properties for disk galaxies. We find that winds from more massive galaxies are hotter and more highly enriched, in stark contrast to that which is often assumed in galaxy formation models. We use these findings in a simple model of galactic enrichment evolution, in which the metallicity of forming galaxies is the result of accretion of nearly pristine gas and outflow of enriched gas along an equilibrium sequence. We compare these predictions to the observed mass-metallicity relation, and demonstrate how the galaxy's gas fraction is a key controlling parameter. This explains the observed flattening of the mass-metallicity relation at higher stellar masses.

19 pages, 15 figures, accepted to MNRAS

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Cited by in corpus (10)

• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• First results from SMAUG: Characterization of Multiphase Galactic Outflows from a Suite of Local Star-Forming Galactic Disk Simulations
• The physics of gas phase metallicity gradients in galaxies
• The mass-metallicity relations for gas and stars in star-forming galaxies: strong outflow vs variable IMF
• MUSE Analysis of Gas around Galaxies (MAGG) -- I: Survey design and the environment of a near pristine gas cloud at z~3.5
• Comparing galaxy formation in semi-analytic models and hydrodynamical simulations
• Mass and star formation rate of the host galaxies of compact binary mergers across cosmic time
• Simple Yet Powerful: Hot Galactic Outflows Driven by Supernovae
• The Production of Cold Gas Within Galaxy Outflows
• The evolution of galaxy metallicity scaling relations in cosmological hydrodynamical simulations