The relation between metallicity, stellar mass and star formation in galaxies: an analysis of observational and model data
The relation between metallicity, stellar mass and star formation in galaxies: an analysis of observational and model data
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DOI：
10.1111/j.1365-2966.2012.20595.x
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发表时间：
2011-07
影响因子：
4.8
通讯作者：
R. Yates;G. Kauffmann;Q. Guo
中科院分区：
文献类型：
--
作者：
R. Yates;G. Kauffmann;Q. Guo
我们研究了来自SDSS-DR 7的177，071个独特发射线星系样本以及来自宇宙学半解析模型L-Galerkin的43，767个z = 0的星星形成星系样本中恒星质量、星星形成和气相金属丰度之间的关系。我们证明，金属丰度是依赖于星星的形成率在固定的质量，但低和高恒星质量的星系的趋势是相反的。正在活跃形成恒星的低质量星系比静止的低质量星系更缺乏金属。另一方面，如果大质量星系的星星形成率很小，则它们的气相金属丰度较低。值得注意的是，在我们的模型星系样本中也发现了同样的趋势。通过研究这些星系中恒星成分、气体和金属随时间的演化，我们对可能导致这些趋势的物理过程有了一些了解。我们发现，具有低气相金属丰度的大质量星系在过去经历了一次富含气体的合并，引发了一次星爆，耗尽了它们的冷气库，并关闭了星星的形成。此后，这些星系能够吸积贫金属气体，但这些气体的密度太低，无法有效地形成恒星。这导致这些系统的气相金属丰度随着时间的推移逐渐稀释。这些模型星系被预测具有低于平均的气体-恒星质量比和高于平均的中心黑洞质量。我们用我们的观测样本来证实，真实的大质量星系与低气相金属也有非常大的黑洞。我们建议，吸积因此可能发挥重要作用，在调节气相金属丰度的大质量星系。
We study relations between stellar mass, star formation and gas-phase metallicity in a sample of 177,071 unique emission line galaxies from the SDSS-DR7, as well as in a sample of 43,767 star forming galaxies at z = 0 from the cosmological semianalytic model L-Galaxies. We demonstrate that metallicity is dependent on star formation rate at fixed mass, but that the trend is opposite for low and for high stellar mass galaxies. Low-mass galaxies that are actively forming stars are more metal-poor than quiescent low-mass galaxies. High-mass galaxies, on the other hand, have lower gas-phase metallicities if their star formation rates are small. Remarkably, the same trends are found for our sample of model galaxies. By examining the evolution of the stellar component, gas and metals as a function of time in these galaxies, we gain some insight into the physical processes that may be responsible for these trends. We find that massive galaxies with low gas-phase metallicities have undergone a gas-rich merger in the past, inducing a starburst which exhausted their cold gas reservoirs and shut down star formation. Thereafter, these galaxies were able to accrete metal-poor gas, but this gas remained at too low a density to form stars efficiently. This led to a gradual dilution in the gas-phase metallicities of these systems over time. These model galaxies are predicted to have lower-than-averagegas-to-stellar mass ratios and higherthan-average central black hole masses. We use our observational sample to confirm that real massive galaxies with low gas-phase metallicities also have very massive black holes. We propose that accretion may therefore play a significant role in regulating the gas-phase metallicities of present-day massive galaxies.