Subgrid Modeling of AGN-driven Turbulence in Galaxy Clusters
Subgrid Modeling of AGN-driven Turbulence in Galaxy Clusters
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DOI：
10.1086/591228
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发表时间：
2008-06
期刊：
影响因子：
--
通讯作者：
E. Scannapieco;M. Brüggen
中科院分区：
文献类型：
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作者：
E. Scannapieco;M. Brüggen
由活跃的银河核（AGN）提供动力的热量不足的气泡在停止酷核星系簇中的灾难性冷却方面起着关键作用。网格水动力代码，Flash3，我们添加了湍流和混合的亚网格模型。分辨率依赖于气体的口袋，适当的亚网格湍流模型表明，这是对湍流级联的近似值，持续远远超出了分辨率的限制。同时，将其保存为连贯的结构，与观察结果一致。在静水内培养基（ICM）中，随着它们在地球的静水气氛中升高，大型空气爆发导致了独特的“蘑菇云”结构。它显着改变了AGN对凉爽核心簇（例如珀尔修斯）中熵和金属分布的影响。
Hot, underdense bubbles powered by active galactic nuclei (AGNs) are likely to play a key role in halting catastrophic cooling in the centers of cool-core galaxy clusters. We present three-dimensional simulations that capture the evolution of such bubbles, using an adaptive mesh hydrodynamic code, FLASH3, to which we have added a subgrid model of turbulence and mixing. While pure hydro simulations indicate that AGN bubbles are disrupted into resolution-dependent pockets of underdense gas, proper modeling of subgrid turbulence indicates that this is a poor approximation to a turbulent cascade that continues far beyond the resolution limit. Instead, Rayleigh-Taylor instabilities act to effectively mix the heated region with its surroundings, while at the same time preserving it as a coherent structure, consistent with observations. Thus, bubbles are transformed into hot clouds of mixed material as they move outward in the hydrostatic intracluster medium (ICM), much as large airbursts lead to a distinctive “mushroom cloud” structure as they rise in the hydrostatic atmosphere of Earth. Properly capturing the evolution of such clouds has important implications for many ICM properties. In particular, it significantly changes the impact of AGNs on the distribution of entropy and metals in cool-core clusters such as Perseus.