泵铁：湍流金属扩散如何影响多相星系外流
Pumping Iron: How turbulent metal diffusion impacts multiphase galactic outflows
AI总结：
本研究通过高分辨率模拟，探究湍流金属扩散对矮星系多相外流的影响，发现其显著影响热相冷却与声速，但对载荷因子影响微弱。
摘要：
大多数星系形成与演化的数值模拟无法在分辨率尺度或以下正确解析湍流级联，因此需要湍流模型来捕捉这些未分辨尺度上的涡旋运动。在本研究中，我们探究了湍流金属扩散模型对来自矮星系（$M_{\rm halo} \sim 10^{10} - 10^{11}$ M$_\odot$）的多相外流的影响。我们使用最先进的数值模型来模拟单恒星形成、非平衡冷却和氢化学。我们的模拟在质量分辨率约为1 M$_\odot$下进行，其中单个超新星爆炸通过热相生成和动量输入得以分辨。我们发现质量、能量和金属载荷因子受金属扩散模型的影响较弱。当包含金属扩散模型时，星系盘上方低海拔处的金属增丰因子高出约20%。具体而言，我们发现冷星际介质中的冷却效率更高，因为更多金属保留在冷致密相中。金属扩散模型最显著的影响是，在没有金属扩散的情况下，热相冷却更快，声速降低两倍。具体来说，我们发现没有金属扩散时热相金属增丰更多，导致该相更快（过度）冷却，这与我们在有金属扩散的模拟中发现的更高声速一致。
英文摘要：
Most numerical simulations of galaxy formation and evolution are unable to properly resolve the turbulent cascade at or below the resolution scale and turbulence models are required to capture the motion of eddies on those unresolved scales. In this study, we investigate the impact of turbulent metal diffusion models on multiphase outflows originating from dwarf galaxies ($M_{\rm halo} \sim 10^{10} - 10^{11}$ M$_\odot$). We use our state-of-the-art numerical model for the formation of single stars and non-equilibrium cooling and hydrogen chemistry. Our simulations are carried out at a mass resolution of $\sim$1 M$_{\odot}$, where the individual supernova explosions are resolved in terms of hot-phase generation and momentum input. We find that mass, energy, and metal loading factors are only weakly affected by the inclusion of a metal diffusion model. The metal enrichment factor at low altitude above the galactic disk is higher by around 20 per cent when the metal diffusion model is included. Specifically, we find more efficient cooling in the cold interstellar medium, as higher amounts of metals are kept in the cold dense phase. The most striking effect of the metal diffusion model is that, without metal diffusion, there is more rapid cooling in the hot phase and a reduced sound speed by a factor of two. Specifically, we find that the hot phase is more metal enriched in the case without metal diffusion leading to more rapid (over) cooling of that phase which is consistent with the higher sound speed we find in the runs with metal diffusion.
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