The effect of differential galactic winds on the chemical evolution of galaxies
The effect of differential galactic winds on the chemical evolution of galaxies
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DOI：
10.1051/0004-6361:200809879
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发表时间：
2008-08
影响因子：
6.5
通讯作者：
S. Recchi;S. Recchi;E. Spitoni;F. Matteucci;G. Lanfranchi
中科院分区：
文献类型：
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作者：
S. Recchi;S. Recchi;E. Spitoni;F. Matteucci;G. Lanfranchi
目标。本文的目的是研究有气体流动的星系化学演化的基本方程。特别地，我们关注的是流出量不同的模型，即重元素（或某些重元素）比其他化学物质（如H和He）更容易离开母星系。方法。我们在简单模型的框架内研究星系的化学演化，也就是说，我们对恒星的寿命和新产生的金属的混合做出简化的假设。这使我们能够解析地解出气体质量和金属丰度演化的方程。特别是，我们发现新的分析解决方案，在各种情况下，风和降雨的影响被考虑在内。结果。微分星系风，即优先携带金属的风，具有降低星系整体金属丰度的作用，随着金属喷射效率的增加，减少量也在增加。据预测，丰度比在星系的整个演化过程中保持恒定，即使存在不同的风。改变它们的一种方法是假设不同元素的不同喷射效率的不同风。然而，简单的模型只适用于在短时间尺度上产生的元素，即全部由II型SNe产生，因此不同金属的喷射效率不太可能有很大差异。结论。在不包括Ia型超新星产生的铁的情况下，星系中[O/Fe]等丰度比率的变化，原则上可以通过假设O相对于II型超新星损失的铁的不太可能的不同效率来获得。因此，我们得出结论，忽略Ia型超新星是不现实的，一些化学元素相对于其他化学元素的延迟产生（时滞模型）仍然是α-元素相对于Fe的进化最合理的解释。
Aims. The aim of this paper is to study the basic equations of the chemical evolution of galaxies with gas flows. In particular, we focus on models in which the outflow is differential, namely in which the heavy elements (or some of the heavy elements) can leave the parent galaxy more easily than other chemical species such as H and He. Methods. We study the chemical evolution of galaxies in the framework of simple models, namely we make simplifying assumptions about the lifetimes of stars and the mixing of freshly produced metals. This allows us to solve analytically the equations for the evolution of gas masses and metallicities. In particular, we find new analytical solutions for various cases in which the effects of winds and infall are taken into account. Results. Differential galactic winds, namely winds carrying out preferentially metals, have the effect of reducing the global metallicity of a galaxy, with the amount of reduction increasing with the ejection efficiency of the metals. Abundance ratios are predicted to remain constant throughout the whole evolution of the galaxy, even in the presence of differential winds. One way to change them is by assuming differential winds with different ejection efficiencies for different elements. However, simple models apply only to elements produced on short timescales, namely all by type II SNe, and therefore large differences in the ejection efficiencies of different metals are unlikely. Conclusions. Variations in abundance ratios such as [O/Fe] in galaxies, without including the Fe production by type Ia supernovae, can in principle be obtained by assuming an unlikely different efficiency in the loss of O relative to Fe from type II supernovae. Therefore, we conclude that it is not realistic to ignore type Ia supernovae and that the delayed production of some chemical elements relative to others (time-delay model) remains the most plausible explanation for the evolution of α-elements relative to Fe.