Dynamical Equilibrium in the Molecular ISM in 28 Nearby Star-forming Galaxies-猫眼课题宝

DOI：

10.3847/1538-4357/ab781c

发表时间：

2020-02

期刊：

The Astrophysical Journal

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

Jiayi Sun;A. Leroy;E. Ostriker;Annie Hughes;Annie Hughes;E. Rosolowsky;A. Schruba;E. Schinnerer;Guillermo A. Blanc;Guillermo A. Blanc;C. Faesi;J. Kruijssen;S. Meidt;D. Utomo;F. Bigiel;A. Bolatto;M. Chevance;I. Chiang;D. Dale;E. Emsellem;E. Emsellem;S. Glover;K. Grasha;J. Henshaw;C. Herrera;M. Jiménez-Donaire;Janice C. Lee;J. Pety;M. Querejeta;T. Saito;K. Sandstrom;A. Usero

我们将观测到的分子气体中的湍流压力Pturb与星际气体在星系引力势中保持平衡所需的压力PDE进行了比较。为此，我们将PHANGS-ALMA的弧秒分辨率CO数据与追踪附近28个恒星形成星系的原子气体、恒星结构和恒星形成速率(SFR)的多波长数据结合起来。我们发现Pturb与千帕秒尺度上的估计PDE相关--但几乎总是超过估计的PDE。这表明相对于大尺度环境，分子气体处于超压状态。我们发现，这种超压作用可以用分子气体的块状性质来解释；对云层尺度上的PDE的修正估计，解释了分子气体的自引力、外引力和环境压力，与在星系盘中观察到的Pturb很好地吻合。我们还发现，在我们的样本中，云尺度的分子气体更有可能是自引力的，而气压较低的气体似乎更受环境压力和/或外部重力的影响。此外，我们还表明，在大多数情况下，Pturb和观测到的SFR表面密度之比与恒星反馈驱动的动量注入是相容的，而部分区域可能显示出由附加源驱动的湍流的证据。星系盘中Kpc尺度的PDE与自律恒星形成模型的预期是一致的。最后，我们证实了前人报道的分子原子气体比与KPC尺度偏微分方程之间的经验关联。

We compare the observed turbulent pressure in molecular gas, Pturb, to the required pressure for the interstellar gas to stay in equilibrium in the gravitational potential of a galaxy, PDE. To do this, we combine arcsecond resolution CO data from PHANGS-ALMA with multiwavelength data that trace the atomic gas, stellar structure, and star formation rate (SFR) for 28 nearby star-forming galaxies. We find that Pturb correlates with—but almost always exceeds—the estimated PDE on kiloparsec scales. This indicates that the molecular gas is overpressurized relative to the large-scale environment. We show that this overpressurization can be explained by the clumpy nature of molecular gas; a revised estimate of PDE on cloud scales, which accounts for molecular gas self-gravity, external gravity, and ambient pressure, agrees well with the observed Pturb in galaxy disks. We also find that molecular gas with cloud-scale in our sample is more likely to be self-gravitating, whereas gas at lower pressure it appears more influenced by ambient pressure and/or external gravity. Furthermore, we show that the ratio between Pturb and the observed SFR surface density, , is compatible with stellar feedback-driven momentum injection in most cases, while a subset of the regions may show evidence of turbulence driven by additional sources. The correlation between and kpc-scale PDE in galaxy disks is consistent with the expectation from self-regulated star formation models. Finally, we confirm the empirical correlation between molecular-to-atomic gas ratio and kpc-scale PDE reported in previous works.

Dynamical Equilibrium in the Molecular ISM in 28 Nearby Star-forming Galaxies

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