发表机构
The Hebrew University; University of Washington; University of California, Santa Barbara（希伯来大学; 华盛顿大学; 加州大学圣巴巴拉分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究沿宇宙网细丝穿透大质量晕维里冲击的冷流，通过三维模拟改变流半径、马赫数等参数，识别出多种演化模式，揭示了不同压力对比下的物理过程，应用于星系演化框架得出不同红移时冷流的情况。
AI 中文摘要
沿着宇宙网细丝穿透大质量晕维里冲击的冷流有望在高红移时为星系增长提供燃料，但其穿透的物理过程仍不确定。我们使用理想化三维模拟研究穿透热星系际介质（CGM）的圆柱形冷流。系统改变流半径、马赫数和流与CGM之间的初始压力对比，跨越三种密度对比，并在压力平衡重新建立后控制流属性。识别出三种演化模式：凝聚、碎裂和破坏，还有一种临界模式，流核心勉强存活而分离碎片被破坏。在适度压力对比下，存活主要由速度剪切和辐射冷却之间的竞争决定。增加压力对比在压力恢复期间产生瞬态响应，暂时增强或抑制冷气体质量和冷热界面面积，然后演化收敛到剪切主导状态。在更大压力对比下，斜激波变陡成弓形激波，最终结果由激波后冷却时间与维里穿越时间的比率决定。在所有存活情况下，平衡后演化可用流-CGM界面处的湍流辐射夹带很好地描述：冷气体质量通量增加而平均流向动量通量大致守恒。将这些结果应用于星系演化框架，发现在\(z>2\)时高\(\sigma\)密度峰值处的冷流有望存活并可能碎裂成嵌入热CGM的多相结构。在\(z\lesssim0.5\)时，更强的弓形激波和更长的激波后冷却抑制冷流穿透。
英文摘要
Cold streams penetrating virial shocks of massive halos along cosmic web filaments are expected to fuel galaxy growth at high redshift, yet the physical processes governing their penetration remain uncertain. We investigate cylindrical cold streams penetrating a hot circumgalactic medium (CGM) using idealized three-dimensional simulations. We systematically vary the stream radius, Mach number, and initial stream-to-CGM pressure contrast across three density contrasts, while controlling stream properties after pressure equilibrium is re-established. We identify three evolutionary regimes: coagulation, fragmentation, and disruption, plus a borderline regime in which the stream core marginally survives while detached fragments are disrupted. At modest pressure contrast, survival depends primarily on the competition between velocity shear and radiative cooling. Increasing pressure contrast produces a transient response during pressure restoration, temporarily enhancing or suppressing cold-gas mass and cold-hot interfacial area before evolution converges to a shear-dominated state. At larger pressure contrasts, the oblique shock steepens into a bow shock, and the final outcome is determined by the ratio of post-shock cooling time to virial crossing time. In all survival cases, post-equilibration evolution is well described by turbulent radiative entrainment at the stream-CGM interface: cold-gas mass flux increases while mean streamwise momentum flux remains approximately conserved. Applying these results to a galaxy evolution framework, we find that cold streams are expected to penetrate virial shocks around massive halos at $z>2$, though they may fragment into multiphase structures within the hot CGM at $M_\mathrm{v}\gtrsim2\times10^{12}\,\mathrm{M}_\odot$. Toward lower redshift, bow-shock heating and inefficient post-shock cooling can suppress cold-stream penetration.
Comments29 pages, 17 figures, publishsed on MNRAS
