The physical origin of the scatter in the relation between galaxy stellar mass and the metallicity of the interstellar medium, i.e. the mass–metallicity relation (MZR), reflects the relative importance of key processes in galaxy evolution. The eagle cosmological hydrodynamical simulation is used to investigate the correlations between the residuals of the MZR and the residuals of the relations between stellar mass and, respectively, specific inflow, outflow, and star formation rate as well as the gas fraction for central galaxies. At low redshift, all these residuals are found to be anticorrelated with the residuals of the MZR for M⋆/M⊙ ≲ 1010. The correlations between the residuals of the MZR and the residuals of the other relations with mass are interrelated, but we find that gas fraction, specific inflow rate, and specific outflow rate all have at least some independent influence on the scatter of the MZR. We find that, while for M⋆/M⊙ > 1010.4 the specific mass of the nuclear black hole is most important, for M⋆/M⊙ ≲ 1010.3 gas fraction and specific inflow rate are the variables that correlate most strongly with the MZR scatter. The time-scales involved in the residual correlations and the time that galaxies stay above the MZR are revealed to be a few Gyr. However, most galaxies that are below the MZR at z = 0 have been below the MZR throughout their lifetimes.

中文翻译：

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用气流解释星系质量-金属度关系中的散射

星系恒星质量与星际介质金属丰度的关系，即质量-金属丰度关系（MZR）中散射的物理起源，反映了星系演化中关键过程的相对重要性。eagle 宇宙学流体动力学模拟用于研究 MZR 残差与恒星质量残差之间的相关性，分别与特定流入、流出和恒星形成率以及中心星系的气体分数之间的关系。在低红移时，所有这些残差都与 M⋆/M⊙ ≲ 1010 的 MZR 残差反相关。MZR 残差与其他与质量关系的残差之间的相关性是相互关联的，但我们发现该气体分数，特定流入率，和具体流出率都至少对 MZR 的散布有一定的独立影响。我们发现，而对于 M⋆/M⊙ > 1010.4 核黑洞的比质量是最重要的，因为 M⋆/M⊙ ≲ 1010.3 气体分数和比流入率是与 MZR 散射相关性最强的变量。残差相关所涉及的时间尺度和星系停留在 MZR 之上的时间被揭示为几个 Gyr。然而，大多数在 z = 0 时低于 MZR 的星系在其整个生命周期中都低于 MZR。3 气体分数和特定流入率是与 MZR 散射最密切相关的变量。残差相关所涉及的时间尺度和星系停留在 MZR 之上的时间被揭示为几个 Gyr。然而，大多数在 z = 0 时低于 MZR 的星系在其整个生命周期中都低于 MZR。3 气体分数和特定流入率是与 MZR 散射最密切相关的变量。残差相关所涉及的时间尺度和星系停留在 MZR 之上的时间被揭示为几个 Gyr。然而，大多数在 z = 0 时低于 MZR 的星系在其整个生命周期中都低于 MZR。