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arXiv 2602.02657astro-ph.GA
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星际介质的节奏：追踪气体演化和恒星形成在银河环境中的时间尺度

The Rhythm of the ISM: Tracing the Timescales of Gas Evolution and Star Formation across Galactic Environments

University of Maryland, College Park（马里兰大学帕克分校）；Center for Astrophysics, Harvard & Smithsonian（哈佛-史密森尼天体物理中心）

Zuzanna Kocjan, Vadim A. Semenov

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22 pages, 13 figures, submitted to ApJ, comments welcome
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AI总结：

研究揭示了银河系中恒星形成时间尺度与星际介质湍流及气体状态的相互作用，显示气体循环和恒星形成过程在不同环境下的变化规律。

摘要：

我们研究了气体耗尽时间、恒星形成气体质量分数和气体面密度$\Sigma_{\rm gas}$之间的恒星形成标度关系，这些都在千秒差距尺度上，都是观测到的肯尼库特-施密特关系的关键组成部分。为了阐明这些趋势，我们采用了一个分析框架，明确地将这些千秒差距尺度的性质与支配单个恒星形成区域内快速连续星际介质（ISM）气体循环的时间尺度联系起来，包括恒星形成气体的形成、分散和局部耗尽。使用一系列理想化的盘状星系模拟，涵盖了从矮星系和银河质量系统到富含气体的星爆类比系统等多种环境，我们测量了气体循环的时间尺度，并将其与星际介质（ISM）的动力学和湍流性质联系起来。我们发现，恒星形成区域的形成时间接近银河盘的垂直湍流穿越时间，约为3-30 Myr，在更高的$\Sigma_{\rm gas}$下由于ISM中湍流速度的增加和盘厚度的减小而减少。相比之下，局部恒星形成和此类气体的分散则由局部条件决定。具体而言，局部耗尽时间约为200-2000 Myr，在更高的$\Sigma_{\rm gas}$下减少，因为恒星形成气体变得更加密集和高效地形成恒星。此类气体的寿命非常短，约为0.4-1 Myr，并且仅弱相关于$\Sigma_{\rm gas}$。总的来说，我们的结果展示了银河系在千秒差距尺度上的恒星形成特性如何直接来自银河系尺度的动力学、星际介质湍流以及恒星形成气体的状态之间的相互作用。

英文摘要：

We investigate the physical origin of the star formation scaling relations between the gas depletion time, the star-forming gas mass fraction, and the gas surface density, $Σ_{\rm gas}$, on kiloparsec scales, all of which are the key ingredients of the observed Kennicutt-Schmidt relation. To elucidate these trends, we employ an analytical framework that explicitly connects these kiloparsec-scale properties to the timescales governing the rapid, continuous ISM gas cycle on the scales of individual star-forming regions, including the formation, dispersal, and local depletion of star-forming gas. Using a suite of idealized disk galaxy simulations spanning a range of environments from dwarf and Milky Way-mass systems to a gas-rich starburst analog, we measure the timescales of the gas cycle and relate them to the dynamical and turbulent properties of the interstellar medium (ISM). We find that star-forming regions form on a timescale close to the vertical turbulent crossing time of the galactic disk, $\sim$3-30 Myr, which decreases at higher $Σ_{\rm gas}$ due to the increase in turbulent velocities in the ISM and the decrease in the disk thickness. In contrast, the local star formation and dispersal of such gas are set by the local conditions. Specifically, the local depletion time, $\sim$200-2000 Myr, is decreasing at higher $Σ_{\rm gas}$, as star-forming gas becomes denser and more efficient in forming stars. The lifetime of such gas is very short, $\sim$0.4-1 Myr, and only weakly increases with $Σ_{\rm gas}$. Together, our results demonstrate how the star formation properties of galaxies on kiloparsec scales emerge directly from the interplay between the galaxy-scale dynamics, ISM turbulence, and the state of star-forming gas.

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