Great balls of FIRE – I. The formation of star clusters across cosmic time in a Milky Way-mass galaxy
Great balls of FIRE – I. The formation of star clusters across cosmic time in a Milky Way-mass galaxy
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巨大的火球 — I. 银河系质量星系中跨越宇宙时间的星团形成
DOI：
10.1093/mnras/stac3573
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发表时间：
2022
影响因子：
4.8
通讯作者：
Faucher-Giguère, Claude-André
中科院分区：
文献类型：
--
作者：
Grudić, Michael Y.;Hafen, Zachary;Rodriguez, Carl L.;Guszejnov, Dávid;Lamberts, Astrid;Wetzel, Andrew;Boylan-Kolchin, Michael;Faucher-Giguère, Claude-André
人们认为，星系内形成的年轻星团的特性在不同的星际介质条件下会有所不同，但由于星系和星团形成涉及的动态范围很大，人们对从星系到星团尺度的映射细节知之甚少。我们引入了一种在星系模拟中对星团形成进行建模的新方法：根据校准到更高分辨率模拟的 GMC 规模星团形成模型，将 FIRE-2 磁流体动力学星系模拟中自洽形成的巨分子云 (GMC) 映射到星团群体上，获得星系星团在质量、金属丰度、空间和时间方面的详细属性。我们发现，星系中形成的所有恒星总体上都起源于引力束缚的星团，并且这一比例在 Σgas 和 ΣSFR 升高的区域中增加，因为这些区域拥有更密集的 GMC，具有更高的恒星形成效率。这些数量在星系的历史中系统地变化，推动了星团形成的变化。束缚团簇的质量函数各不相同——没有任何单一的类谢克特分布或幂律分布始终适用。在最极端的情况下，质量达 7 × 106M⊙ 的星团会在巨大而致密的云中形成，具有很高的恒星形成效率。年轻星团的初始质量半径关系与环境相关的 3D 密度一致，该密度随着 Σgas 和 ΣSFR 的增加而增加。该模型没有重现银河系中发现的旧 () 球状星团的年龄和金属丰度统计数据，可能是因为它在 z> 3 时形成恒星的速度更慢。
The properties of young star clusters formed within a galaxy are thought to vary in different interstellar medium conditions, but the details of this mapping from galactic to cluster scales are poorly understood due to the large dynamic range involved in galaxy and star cluster formation. We introduce a new method for modelling cluster formation in galaxy simulations: mapping giant molecular clouds (GMCs) formed self-consistently in a FIRE-2 magnetohydrodynamic galaxy simulation on to a cluster population according to a GMC-scale cluster formation model calibrated to higher resolution simulations, obtaining detailed properties of the galaxy’s star clusters in mass, metallicity, space, and time. We findof all stars formed in the galaxy originate in gravitationally bound clusters overall, and this fraction increases in regions with elevated Σgasand ΣSFR, because such regions host denser GMCs with higher star formation efficiency. These quantities vary systematically over the history of the galaxy, driving variations in cluster formation. The mass function of bound clusters varies – no single Schechter-like or power-law distribution applies at all times. In the most extreme episodes, clusters as massive as 7 × 106M⊙form in massive, dense clouds with high star formation efficiency. The initial mass–radius relation of young star clusters is consistent with an environmentally dependent 3D density that increases with Σgasand ΣSFR. The model does not reproduce the age and metallicity statistics of old () globular clusters found in the Milky Way, possibly because it forms stars more slowly atz> 3.