冷核团簇中空腔驱动的气体输运：对多相气体冷却的启示
Cavity-driven Gas Transport in Cool-Core Clusters: Implications for Multiphase Gas Cooling
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中文总结 AI 辅助
本研究通过24个冷核星系团样本，量化空腔抬升气体的参数空间，发现分子气体质量与空腔置换质量线性相关，支持反复AGN爆发抬升气体促进低熵气体凝结并构建分子储库的机制。
中文摘要 AI 辅助
我们展示了一项关于空腔抬升气体及其在促进冷核星系团中分子气体形成作用的研究。利用24个星系团的样本，我们量化了气体抬升的参数空间，包括抬升质量、速度、半径和冷却时间，并将被置换的热气体与观测到的分子气体质量进行比较。几乎所有星系团在中心约10千秒差距内都含有足够的低熵气体，足以解释观测到的分子气体。分子气体质量大致与空腔置换的最大气体质量呈线性关系。冷却时间为几亿年的气体可以被输运到典型的Hα纤维半径10-30千秒差距处，特征速度为150-400公里/秒，而冷却时间约为10^9年的气体通常需要抬升到约60千秒差距以上。在假设50%的被置换气体被抬升并冷却的情况下，在当前观测到的空腔寿命内预期冷却的质量与几个系统中的分子储库相当，而其他系统则含有过量的分子气体。这表明分子气体储库可能是在多次涉及气体反复抬升和冷却的AGN反馈循环中积累起来的，或通过其他过程形成。Hα和红外光度随X射线冷却光度线性增加，将多相发射与冷却大气联系起来。总体而言，我们的结果支持这样一种图景：反复的AGN爆发伴随着气体抬升，促进了低熵气体的凝结，并有助于在冷核 brightest cluster galaxy 中建立分子储库。
英文摘要
We present a study of gas uplift by cavities and its role in promoting the formation of molecular gas in cool-core galaxy clusters. Using a sample of 24 clusters, we quantify the parameter space of gas uplift, including lifting masses, velocities, radii, and cooling times, and compare the displaced hot gas to observed molecular gas masses. Almost all clusters contain sufficient low-entropy gas within the central $\sim$10 kpc to account for the observed molecular gas. The molecular gas mass scales approximately linearly with the maximum gas mass displaced by cavities. Gas with cooling times of a few $10^8$ yr can be transported to typical H$α$ filament radii of 10--30 kpc at characteristic velocities of 150--400 km s$^{-1}$, whereas gas with $t_{\rm cool}\sim10^9$ yr generally requires uplift to $\gtrsim60$ kpc. The mass expected to cool over the lifetimes of the currently observed cavities is comparable to the molecular reservoir in several systems, assuming that 50\% of the displaced gas mass is lifted and cools, whereas other systems contain excess molecular gas. This suggests that the molecular gas reservoirs may have accumulated over multiple AGN feedback cycles involving repeated gas uplift and cooling, or through additional processes. H$α$ and infrared luminosities increase linearly with X-ray cooling luminosity, linking the multiphase emission to the cooling atmosphere. Overall, our results support a picture in which repeated AGN outbursts with gas uplift promote the condensation of low-entropy gas and help build molecular reservoirs in cool-core BCGs.
发表机构
- University of Alabama in Huntsville（亨茨维尔阿拉巴马大学）
- University of Waterloo（滑铁卢大学）
- ICRAR, Perth, Western Australia（西澳大利亚珀斯 ICRAR）
- Harvard-Smithsonian center for Astrophysics（哈佛-史密森尼天体物理中心）
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