Dynamically Driven Inflow onto the Galactic Center and its Effect upon Molecular Clouds
Dynamically Driven Inflow onto the Galactic Center and its Effect upon Molecular Clouds
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DOI：
10.3847/1538-4357/ac1e89
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发表时间：
2021-06
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影响因子：
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通讯作者：
H. P. Hatchfield;M. Sormani;R. Tress;C. Battersby;Rowan J. Smith;S. Glover;R. Klessen
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文献类型：
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作者：
H. P. Hatchfield;M. Sormani;R. Tress;C. Battersby;Rowan J. Smith;S. Glover;R. Klessen
银河系棒在银河系中央分子带(CMZ)的演化中扮演着关键角色，通过被称为尘埃通道的气体流动将气体驱动到银河系中心。为了探索CMZ和尘埃通道之间的相互作用，我们在AREPO中进行了流体力学模拟，在没有气体自重和恒星形成物理的情况下模拟了银河系条形的势能，并使用蒙特卡罗示踪粒子研究了质量流动。我们估计了通过尘埃通道流入的效率，发现只有大约三分之一(30%±12%)的尘埃通道质量最初附着在CMZ上，而其余的质量超载并在稍后沉积。根据对银河系尘埃带内气体数量的观测估计，这表明进入CMZ的真实总流量为0.8±0.6M⊙yr−1。在这个模拟的CMZ中，云的平均密度在远地点附近突然达到峰值，在那里它们与流入的物质发生猛烈碰撞。虽然这些云由于切变而倾向于逆旋转，但由于与流入物质的碰撞产生的动量注入，偶尔也会出现同旋云(∼52%是强对旋云，∼7%是44云样本的强同旋云)。我们研究了这些云的形成和演化，发现它们是由许多离散的流入事件提供的，即使它们坍塌并形成恒星，也为CMZ云提供了一致的气体来源。
The Galactic bar plays a critical role in the evolution of the Milky Way’s Central Molecular Zone (CMZ), driving gas toward the Galactic Center via gas flows known as dust lanes. To explore the interaction between the CMZ and the dust lanes, we run hydrodynamic simulations in arepo, modeling the potential of the Milky Way’s bar in the absence of gas self-gravity and star formation physics, and we study the flows of mass using Monte Carlo tracer particles. We estimate the efficiency of the inflow via the dust lanes, finding that only about a third (30% ± 12%) of the dust lanes’ mass initially accretes onto the CMZ, while the rest overshoots and accretes later. Given observational estimates of the amount of gas within the Milky Way’s dust lanes, this suggests that the true total inflow rate onto the CMZ is 0.8 ± 0.6 M ⊙ yr−1. Clouds in this simulated CMZ have sudden peaks in their average density near the apocenter, where they undergo violent collisions with inflowing material. While these clouds tend to counter-rotate due to shear, co-rotating clouds occasionally occur due to the injection of momentum from collisions with inflowing material (∼52% are strongly counter-rotating, and ∼7% are strongly co-rotating of the 44 cloud sample). We investigate the formation and evolution of these clouds, finding that they are fed by many discrete inflow events, providing a consistent source of gas to CMZ clouds even as they collapse and form stars.