The circumgalactic medium (CGM) is responsive to kinetic disruptions generated by nearby astrophysical events. In this work, we study the saturation and dissipation of turbulent hydrodynamics within the CGM through an extensive array of 252 numerical simulations with proper cooling mechanisms and a large parameter space spanning average gas density, metallicity, and turbulence driving strength. A dichotomy emerges in the dynamics dissipation behaviors upon turbulence driving turnoff. Hot and subsonic disturbances are characterized by weak compression and slow dissipation, while warm and supersonic turbulences are marked by significant compression shocks and subsequent rapid cooling. In the supersonic cases, the kinetic energy decay is divided into a rate-limiting phase of shock dissipation and a comparatively swift phase of thermal dissipation, predominantly occurring within the overdense regions. Dense clouds are crushed on relatively brief timescales of ∼30–100 Myr, depending on turbulence driving strength but independent from average gas density. This independence is in spite of the complex interplay between the kinetics and thermodynamics of dissipation. The brevity of such timescales relative to typical dynamical timescales within the CGM suggests turbulent clouds must be cotemporal with turbulence driving sources such as cool accretion flows or feedback from the interstellar medium. Quantitative results from this work contribute a novel data set of dissipation timescales that incorporates thermodynamics and radiative cooling in an area of study typically focused on kinematics, which may serve as a valuable asset for forthcoming simulations that aim to explore gas dynamics on galactic and cosmological scales.

中文翻译：

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银河系周围介质中均匀驱动绝热湍流的云破碎和消散


银河系周围介质 （CGM） 对附近天体物理事件产生的动力学干扰有反应。在这项工作中，我们通过广泛的 252 个数值模拟来研究 CGM 内湍流流体动力学的饱和和耗散，这些模拟具有适当的冷却机制和涵盖平均气体密度、金属丰度和湍流驱动强度的大参数空间。湍流驱动关闭时的动力学耗散行为出现了二分法。热扰动和亚音速扰动的特点是压缩较弱且消散缓慢，而暖湍流和超音速扰动的特点是显著的压缩冲击和随后的快速冷却。在超音速情况下，动能衰减分为减震的限速阶段和相对快速的热耗散阶段，主要发生在过密集区域。致密的云在 ∼30-100 Myr 的相对较短的时间尺度上被粉碎，这取决于湍流驱动强度，但与平均气体密度无关。尽管耗散的动力学和热力学之间存在复杂的相互作用，但这种独立性仍然存在。相对于 CGM 中的典型动态时间尺度，这种时间尺度的简短表明，湍流云必须与湍流驱动源（如冷吸积流或来自星际介质的反馈）同时期。这项工作的定量结果有助于建立一个新的耗散时间尺度数据集，该数据集将热力学和辐射冷却纳入通常专注于运动学的研究领域，这可能成为即将到来的旨在探索银河系和宇宙学尺度上的气体动力学的模拟的宝贵资产。