Numerical simulations have become a major tool for understanding galaxy formation and evolution. Over the decades the field has made significant progress. It is now possible to simulate the formation of individual galaxies and galaxy populations from well-defined initial conditions with realistic abundances and global properties. An essential component of the calculation is to correctly estimate the inflow to and outflow from forming galaxies because observations indicating low formation efficiency and strong circumgalactic presence of gas are persuasive. Energetic “feedback” from massive stars and accreting supermassive black holes—generally unresolved in cosmological simulations—plays a major role in driving galactic outflows, which have been shown to regulate many aspects of galaxy evolution. A surprisingly large variety of plausible subresolution models succeeds in this exercise. They capture the essential characteristics of the problem, i.e., outflows regulating galactic gas flows, but their predicti...

中文翻译：

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星系形成的理论挑战

数值模拟已成为理解星系形成和演化的主要工具。几十年来，该领域取得了重大进展。现在可以根据具有现实丰度和全球特性的明确初始条件模拟单个星系和星系群的形成。计算的一个重要组成部分是正确估计形成星系的流入和流出，因为观测表明低形成效率和强烈的环星系气体存在是有说服力的。来自大质量恒星和吸积超大质量黑洞的能量“反馈”——在宇宙学模拟中通常没有解决——在驱动星系外流方面发挥着重要作用，已被证明可以调节星系演化的许多方面。在这个练习中，各种各样的似是而非的亚分辨率模型都取得了成功。他们捕捉到了问题的本质特征，即调节银河气体流动的外流，但他们的预测……