Apostle--Auriga：恒星反馈亚网格模型对盘星系角动量演化的影响
Apostle--Auriga: Effects of stellar feedback subgrid models on the evolution of angular momentum in disc galaxies
AI总结：
本文利用 Apostle--Auriga 模拟对比不同恒星反馈亚网格模型，发现 Auriga 盘星系因更多气体经历循环喷泉并与高角动量环星系介质混合而获得更高比角动量，而 Apostle 中该过程较弱，从而解释了二者现今角动量差异。
摘要：
利用 Apostle--Auriga 模拟——这些模拟从类本星系群系统的相同缩放初始条件出发，但使用不同的星系形成亚网格模型和流体动力学求解器——我们研究了恒星反馈模型对盘星系角动量演化的影响。在 $z = 0$ 时，与交叉匹配的 Apostle 对应星系相比，Auriga 盘星系往往表现出更高的比角动量。通过追踪 $z = 0$ 星系中原地恒星粒子的拉格朗日质量示踪剂的演化历史，我们发现两个模拟中气体示踪剂在晕吸积时刻的比角动量分布相对相似。现今的角动量差异主要由暗物质晕内部发生的物理过程驱动，尤其是星系喷泉。由于恒星反馈过程的亚网格实现不同，Auriga 星系含有高比例经历过循环喷泉的气体（约 65%），这些气体可以通过与高角动量环星系介质（CGM）混合而获得角动量。然而，在 Apostle 中，经历循环喷泉过程的气体比例显著较低（对于银河系大小的星系低至约 20%），并且从 CGM 获得的角动量是微不足道的。因此，现今的 Auriga 星系总体上具有更高的比角动量。
英文摘要：
Utilizing the Apostle--Auriga simulations, which start from the same zoom-in initial conditions of Local Group-like systems but run with different galaxy formation subgrid models and hydrodynamic solvers, we study the impact of stellar feedback models on the evolution of angular momentum in disc galaxies. At $z = 0$, Auriga disc galaxies tend to exhibit higher specific angular momenta compared to their cross-matched Apostle counterparts. By tracing the evolution history of the Lagrangian mass tracers of the in-situ star particles in the $z = 0$ galaxies, we find that the specific angular momentum distributions of the gas tracers from the two simulations at the halo accretion time are relatively similar. The present-day angular momentum difference is mainly driven by the physical processes occurring inside dark matter haloes, especially galactic fountains. Due to the different subgrid implementations of stellar feedback processes, Auriga galaxies contain a high fraction of gas that has gone through recycled fountain (${\sim} 65$ per cent) which could acquire angular momentum through mixing with the high angular momentum circumgalactic medium (CGM). In Apostle, however, the fraction of gas that has undergone the recycled fountain process is significantly lower (down to ${\sim} 20$ per cent for Milky Way-sized galaxies) and the angular momentum acquisition from the CGM is marginal. As a result, the present-day Auriga galaxies overall have higher specific angular momenta.
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