We numerically investigate the evolution of compact high-velocity clouds (CHVCs) passing through a hot, tenuous gas representing the highly-ionized circumgalactic medium (CGM) by applying the adaptive-mesh refinement code Flash. The model clouds start from both hydrostatic and thermal equilibrium and are in pressure balance with the CGM. Here, we present 14 models, divided into two mass categories and two metallicities each and different velocities. We allow for selfgravity and thermal conduction or not. All models experience mass diffusion, radiative cooling, and external heating leading to dissociation and ionization. Our main findings are: 1) self-gravity stabilizes clouds against Rayleigh-Taylor instability which are disrupted within 10 sound-crossing times without; 2) clouds can develop Jeans-instable regions internally even though they are initially below Jeans mass; 3) all clouds lose mass by ram pressure and Kelvin-Helmholtz instability; 4) thermal conduction substantially lowers mass-loss rates, by this, extending the clouds’ lifetimes, particularly, more than doubling the lifetime of low-mass clouds; 5) thermal conduction leads to continuous, filamentary stripping, while the removed gas is heated up quickly and mixes efficiently with the ambient CGM; 6) without thermal conduction the removed gas consists of dense, cool, clumpy fragments; 7) thermal conduction might prevent CHVCs from forming stars; 8) clouds decelerated by means of drag from the ambient CGM form head-tail shapes and collapse after they reach velocities characteristic for intermediate-velocity clouds. Conclusively, only sophisticated modelling of CHVCs as non-homogeneous and non-isothermal clouds with thermal conduction and self-gravity explains observed morphologies and naturally leads to the suppression of star formation.

中文翻译：

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对环绕星系介质中致密高速云的物理效应

我们通过应用自适应网格细化代码 Flash，数值研究了致密高速云 (CHVC) 通过代表高度电离的环星系介质 (CGM) 的热、稀薄气体的演化。模型云从流体静力平衡和热平衡开始，并与 CGM 处于压力平衡。在这里，我们展示了 14 个模型，分为两个质量类别和两个金属量，每个模型都有不同的速度。我们是否允许自重和热传导。所有模型都会经历质量扩散、辐射冷却和导致解离和电离的外部加热。我们的主要发现是：1）自重力使云稳定，抵抗瑞利-泰勒不稳定性，而这些不稳定性在 10 次声音交叉时间内被破坏；2）云可以在内部形成牛仔裤不稳定区域，即使它们最初低于牛仔裤质量；3）所有云都因撞击压力和开尔文-亥姆霍兹不稳定性而失去质量；4）热传导大大降低了质量损失率，从而延长了云的寿命，特别是使低质量云的寿命增加了一倍以上；5) 热传导导致连续的丝状剥离，同时去除的气体被快速加热并与环境 CGM 有效混合；6) 没有热传导，排出的气体由致密的、冷的、块状的碎片组成；7) 热传导可能会阻止 CHVCs 形成恒星；8）通过来自环境 CGM 的阻力减速的云在达到中速云的特征速度后形成头尾形状并坍塌。最后，