Ubiquitous velocity fluctuations throughout the molecular interstellar medium
Ubiquitous velocity fluctuations throughout the molecular interstellar medium
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DOI：
10.1038/s41550-020-1126-z
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发表时间：
2020-07
期刊：
影响因子：
14.1
通讯作者：
J. Henshaw;J. Kruijssen;S. Longmore;M. Riener;A. Leroy;E. Rosolowsky;A. Ginsburg;C. Battersby
中科院分区：
文献类型：
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作者：
J. Henshaw;J. Kruijssen;S. Longmore;M. Riener;A. Leroy;E. Rosolowsky;A. Ginsburg;C. Battersby
星际介质的密度结构决定了恒星形成和释放能量、动量和重元素的位置，从而驱动星系演化，, –。密度变化是由气体运动产生和放大的，但这种运动的确切性质在空间尺度和银河环境中是未知的。尽管致密的恒星形成气体可能是由不稳定性、会聚流和湍流的组合产生的，但确定精确的起源具有挑战性，因为它需要在空间尺度上多个数量级上量化气体运动。在这里，我们测量了银河系和附近星系 NGC 4321 中分子气体的运动，收集了跨越空间动态范围 10−1–103pc 的观测结果。我们检测到所有空间尺度和银河环境中普遍存在的速度波动。对这些波动的统计分析表明了恒星形成气体是如何聚集的。我们发现振荡气流的波长范围为 0.3–400 pc。这些流动与可能通过重力不稳定性形成的规则间隔的密度增强相耦合。我们还识别了随机且无标度的速度和密度波动，与湍流中产生的结构一致。我们的结果表明，星际介质的结构不能孤立地考虑。相反，它的形成和演化是由空间尺度上多个数量级的嵌套的、相互依赖的物质流控制的。
The density structure of the interstellar medium determines where stars form and release energy, momentum and heavy elements, driving galaxy evolution, , –. Density variations are seeded and amplified by gas motion, but the exact nature of this motion is unknown across spatial scales and galactic environments. Although dense star-forming gas probably emerges from a combination of instabilities,, convergent flows and turbulence, establishing the precise origin is challenging because it requires gas motion to be quantified over many orders of magnitude in spatial scale. Here we measure, –the motion of molecular gas in the Milky Way and in nearby galaxy NGC 4321, assembling observations that span a spatial dynamic range 10−1–103pc. We detect ubiquitous velocity fluctuations across all spatial scales and galactic environments. Statistical analysis of these fluctuations indicates how star-forming gas is assembled. We discover oscillatory gas flows with wavelengths ranging from 0.3–400 pc. These flows are coupled to regularly spaced density enhancements that probably form via gravitational instabilities,. We also identify stochastic and scale-free velocity and density fluctuations, consistent with the structure generated in turbulent flows. Our results demonstrate that the structure of the interstellar medium cannot be considered in isolation. Instead, its formation and evolution are controlled by nested, interdependent flows of matter covering many orders of magnitude in spatial scale.