Production of Cool Gas in Thermally Driven Outflows
Production of Cool Gas in Thermally Driven Outflows
复制标题
DOI：
10.3847/1538-4357/aacce1
复制
发表时间：
2018-03
期刊：
影响因子：
--
通讯作者：
E. Schneider;B. Robertson;T. Thompson
中科院分区：
文献类型：
--
作者：
E. Schneider;B. Robertson;T. Thompson
银河系流出物通常包含多相气体，其物理起源需要解释。利用高分辨率孤立星系模型的全罗星系流出模拟套件，我们证明了快速辐射冷却作为快速移动（v ~ 1000 km s−1），冷却（104 K）气体来源的可行性，这些气体是在一些恒星形成星系周围流出的吸收线研究中观察到的。通过改变模拟风的质量载荷和几何形状，我们确定了一个参数空间区域，该区域导致流出的冷却气体。特别是，当使用解析驱动的中心反馈模型时，我们发现，在恒星形成率表面密度较高的情况下，可以以合理的质量加载率（）产生冷却流。当应用更真实的聚类反馈模型时，圆盘附近高密度云的破坏和不同流出区之间的相互作用表明，反馈区域内较低的热气体质量加载率仍然可能产生多相流出。这些结果表明，在流出物中快速移动的冷气体的起源并不依赖于直接加速来自星际介质的冷气体。这些冷却流可能还为在低红移恒星形成星系的晕中普遍观察到的多相气体提供了解释。
Galactic outflows commonly contain multiphase gas, and its physical origin requires explanation. Using the Cholla Galactic OutfLow Simulations suite of high-resolution isolated galaxy models, we demonstrate the viability of rapid radiative cooling as a source of fast-moving (v ∼ 1000 km s−1), cool (104 K) gas observed in absorption-line studies of outflows around some star-forming galaxies. By varying the mass loading and geometry of the simulated winds, we identify a region of parameter space that leads to cool gas in outflows. In particular, when using an analytically motivated central feedback model, we find that cooling flows can be produced with reasonable mass-loading rates ( ), provided that the star formation rate surface density is high. When a more realistic clustered feedback model is applied, destruction of high-density clouds near the disk and interactions between different outflow regions indicate that lower mass-loading rates of the hot gas within the feedback region may still produce multiphase outflows. These results suggest an origin for fast-moving cool gas in outflows that does not rely on directly accelerating cool gas from the interstellar medium. These cooling flows may additionally provide an explanation for the multiphase gas ubiquitously observed in the halos of star-forming galaxies at low redshift.