An analytic model for the evolution of the stellar, gas and metal content of galaxies
An analytic model for the evolution of the stellar, gas and metal content of galaxies
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DOI：
10.1111/j.1365-2966.2011.20148.x
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发表时间：
2011-08
影响因子：
4.8
通讯作者：
R. Dav'e;K. Finlator;B. Oppenheimer
中科院分区：
文献类型：
--
作者：
R. Dav'e;K. Finlator;B. Oppenheimer
我们提出了一种描述星系中恒星、气体和金属含量演化的解析形式。它基于这样一种观点，即星系在流入、流出和恒星形成之间处于缓慢演变的平衡状态，这一想法受到了流体动力学模拟的启发。我们认为，这种形式主义广泛地捕捉了在模拟中演化的星系属性的行为。由此得到的恒星形成率、气体分数和金属丰度的平衡方程取决于三个关键的自由参数，这三个参数分别代表抛射反馈、预防性反馈和抛射物质的再凝聚。我们示意性地描述了这些参数如何受到模型和观测的约束。由于流入的随机性而扰乱了平衡关系的星系往往会被驱回到平衡状态，这样，在给定质量下，恒星形成率的偏差与气体分数相关，而与金属丰度反相关。在经历了早期的气体积累时期后，静止的恒星形成星系预计将在宇宙的大部分时间内处于平衡状态。平衡模型为理解星系属性的宇宙演化提供了一个简单直观的框架，并以星系与周围气体之间的重子循环为核心，作为星系增长的驱动力。
We present an analytic formalism that describes the evolution of the stellar, gas and metal content of galaxies. It is based on the idea, inspired by hydrodynamic simulations, that galaxies live in a slowly evolving equilibrium between inflow, outflow and star formation. We argue that this formalism broadly captures the behaviour of galaxy properties evolving in simulations. The resulting equilibrium equations for the star formation rate, gas fraction and metallicity depend on three key free parameters that represent ejective feedback, preventive feedback and reaccretion of ejected material. We schematically describe how these parameters are constrained by models and observations. Galaxies perturbed off the equilibrium relations owing to inflow stochasticity tend to be driven back towards equilibrium, such that deviations in star formation rate at a given mass are correlated with gas fraction and anticorrelated with metallicity. After an early gas accumulation epoch, quiescently star-forming galaxies are expected to be in equilibrium over most of cosmic time. The equilibrium model provides a simple intuitive framework for understanding the cosmic evolution of galaxy properties, and centrally features the cycle of baryons between galaxies and surrounding gas as the driver of galaxy growth.