星系际介质中Turbulence产生和紊流压力支持
Turbulence production and turbulent pressure support in the intergalactic medium
摘要：
利用网格流体动力学模拟方法研究了星系际介质中湍流的注入和演化，其中包括一个亚网格尺度（SGS）小尺度湍流模型。模拟结果表明，在团内介质（ICM）和暖热星系际介质（WHIM）中，湍流的产生具有不同的红移依赖性。我们发现，在ICM中的湍流主要是由合并引起的剪切流，而在WHIM的生产是由激波相互作用为主。其次，研究了动压支承对引力收缩的影响。在重子超密度为1 < delta < 100的WHIM气体中，这种湍流支持更强，与ICM的相关性较小。虽然具有大涡度的气体的相对质量分数是相当大的（52%的ICM），我们发现，只有约10%的质量，这是动态相关的，即不相关的一个同样大的热压力支持。根据这一结果，一个重要的非热压力支持抵消引力收缩是宇宙流中的局部特征，而不是广泛的特征。
英文摘要：
The injection and evolution of turbulence in the intergalactic medium is studied by means of mesh-based hydrodynamical simulations, including a subgrid scale (SGS) model for small-scale unresolved turbulence. The simulations show that the production of turbulence has a different redshift dependence in the intracluster medium (ICM) and the warm-hot intergalactic medium (WHIM). We show that turbulence in the ICM is produced chiefly by merger-induced shear flows, whereas the production in the WHIM is dominated by shock interactions. Secondly, the effect of dynamical pressure support on the gravitational contraction has been studied. This turbulent support is stronger in the WHIM gas at baryon overdensities 1 < delta < 100, and less relevant for the ICM. Although the relative mass fraction of the gas with large vorticity is considerable (52% in the ICM), we find that for only about 10% in mass this is dynamically relevant, namely not associated to an equally large thermal pressure support. According to this result, a significant non-thermal pressure support counteracting the gravitational contraction is a localised characteristic in the cosmic flow, rather than a widespread feature.
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