What causes the formation of discs and end of bursty star formation?
What causes the formation of discs and end of bursty star formation?
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是什么导致了圆盘的形成和爆发式恒星形成的结束？
DOI：
10.1093/mnras/stad1902
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发表时间：
2023
影响因子：
4.8
通讯作者：
Wetzel, Andrew
中科院分区：
文献类型：
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作者：
Hopkins, Philip F.;Gurvich, Alexander B.;Shen, Xuejian;Hafen, Zachary;Grudić, Michael Y.;Kurinchi-Vendhan, Shalini;Hayward, Christopher C.;Jiang, Fangzhou;Orr, Matthew E.;Wetzel, Andrew
随着星系的生长，它们可以从具有“突发”星星形成历史（SFHS）的不规则/球状过渡到具有平滑SFHS的盘状。但即使在模拟中，这种转变的直接物理原因仍然不清楚。因此，我们在一个大型的数值实验中探索这一点，这些实验重新运行了具有广泛不同物理学的宇宙学模拟部分，并进一步验证了现有的FIRE模拟。我们发现，气体供应，冷却/热力学，星星形成模型，Toomre标度，星系动力学时间，和反馈属性不具有直接的因果关系，这些转变。相反，圆盘的形成和爆发性星星形成的停止都是由引力势驱动的，但方式不同。光盘形成促进时，质量分布成为足够集中的形状（相对于圆化半径）：我们表明，这提供了一个明确的动力学中心，停止支持全球的“呼吸模式”，可以无限期地持续在不太集中的配置文件，并有效地摧毁光盘，促进轨道混合，形成一个连贯的角动量，并稳定光盘。光滑SF由势或逃逸速度Vesc（不是圆速度Vc）在星星形成的半径处变得足够大而促进，使得冷的、质量负载（动量守恒）的外流被捕获/限制在星系附近，而不是在爆发后逃逸。我们讨论了详细的物理，这些条件如何出现在宇宙学背景下，它们与其他相关的现象（例如内晕维里化，垂直盘“沉降”），和观测。
As they grow, galaxies can transition from irregular/spheroidal with ‘bursty’ star formation histories (SFHs), to discy with smooth SFHs. But even in simulations, the direct physical cause of such transitions remains unclear. We therefore explore this in a large suite of numerical experiments re-running portions of cosmological simulations with widely varied physics, further validated with existing FIRE simulations. We show that gas supply, cooling/thermodynamics, star formation model, Toomre scale, galaxy dynamical times, and feedback properties donothave a direct causal effect on these transitions. Rather, both the formation of discs and cessation of bursty star formation are driven by the gravitational potential, but in different ways. Disc formation is promoted when the mass profile becomes sufficiently centrally concentrated in shape (relative to circularization radii): we show that this provides a well-defined dynamical centre, ceases to support the global ‘breathing modes’ that can persist indefinitely in less-concentrated profiles and efficiently destroy discs, promotes orbit mixing to form a coherent angular momentum, and stabilizes the disc. Smooth SF is promoted by the potential or escape velocityVesc(not circular velocityVc) becoming sufficiently large at the radii of star formation that cool, mass-loaded (momentum-conserving) outflows are trapped/confined near the galaxy, as opposed to escaping after bursts. We discuss the detailed physics, how these conditions arise in cosmological contexts, their relation to other correlated phenomena (e.g. inner halo virialization, vertical disc ‘settling’), and observations.