arXiv 2009.100792020-09astro-ph.GA

HII区恒星反馈的演化

Evolution of Stellar Feedback in HII Regions

Grace M. Olivier, Laura A. Lopez, Anna L. Rosen, Omnarayani Nayak, Megan Reiter, Mark R. Krumholz, Alberto D. Bolatto

备注：: 13 pages, 8 figures, ApJ, in press
DOI：: 10.3847/1538-4357/abd24a

摘要：

在模拟中需要恒星反馈来产生真实的巨分子云（GMC）和星系，但由于有限的数值分辨率，反馈必须使用亚网格模型来实现。观测工作是测试和锚定这些模型的重要手段，但有限的研究已经评估了多种反馈模式的相对动态作用，特别是在HII区域仍然深深嵌入的扩张的最早阶段。在本文中，我们使用多波长（无线电，红外线和X射线）数据，以测量与直接辐射相关的压力（$P_{\rm dir}$），粉尘处理辐射（$P_{\rm IR}$），光电离加热（$P_{\rm HII}$）和恒星风的冲击加热（$P_{\rm X}$）在106个年轻的，解决了半径$\lesssim$ 0.5 pc的HII区域的样本，以确定如何恒星反馈驱动其膨胀。我们发现，$P_{\rm IR}$占主导地位的84%的地区，中位数$P_{\rm dir}$和$P_{\rm HII}$小于中位数$P_{\rm IR}$的因素$\approx 6$和$\approx 9$，分别。基于压力项的径向依赖性，我们证明了在半径为$\sim$ 3 pc时，HII区从$P_{\rm IR}$为主转变为$P_{\rm HII}$为主.我们发现一个中值捕获因子为$f_{\rm trap} \sim$ 8没有任何径向依赖的样品，这表明该值可以通过在子网格反馈模型。此外，我们发现，在我们的样本的大部分，总压力大于重力压力，这表明反馈是足够的，从该地区驱逐气体。

英文摘要：

Stellar feedback is needed to produce realistic giant molecular clouds (GMCs) and galaxies in simulations, but due to limited numerical resolution, feedback must be implemented using subgrid models. Observational work is an important means to test and anchor these models, but limited studies have assessed the relative dynamical role of multiple feedback modes, particularly at the earliest stages of expansion when HII regions are still deeply embedded. In this paper, we use multiwavelength (radio, infrared, and X-ray) data to measure the pressures associated with direct radiation ($P_{\rm dir}$), dust-processed radiation ($P_{\rm IR}$), photoionization heating ($P_{\rm HII}$), and shock-heating from stellar winds ($P_{\rm X}$) in a sample of 106 young, resolved HII regions with radii $\lesssim$0.5 pc to determine how stellar feedback drives their expansion. We find that the $P_{\rm IR}$ dominates in 84% of the regions and that the median $P_{\rm dir}$ and $P_{\rm HII}$ are smaller than the median $P_{\rm IR}$ by factors of $\approx 6$ and $\approx 9$, respectively. Based on the radial dependences of the pressure terms, we show that HII regions transition from $P_{\rm IR}$-dominated to $P_{\rm HII}$-dominated at radii of $\sim$3 pc. We find a median trapping factor of $f_{\rm trap} \sim$ 8 without any radial dependence for the sample, suggesting this value can be adopted in sub-grid feedback models. Moreover, we show that the total pressure is greater than the gravitational pressure in the majority of our sample, indicating that the feedback is sufficient to expel gas from the regions.

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