论文标题
恒星迁移和金属流 - 模拟银河系的薄盘的化学演变类似星系
Stellar migrations and metal flows -- Chemical evolution of the thin disc of a simulated Milky Way analogous galaxy
论文作者
论文摘要
为了了解金属流在星系形成和进化中的作用，我们分析了在薄盘阶段像银河系一样的银河系的自洽宇宙学化学模拟。我们模拟的星系盘定性地再现了[$α$/fe] - [fe/h]在Apogee-dr16中得出的不同星系中心距离上的[$α$/fe/h]的变化，以及[$α$/fe/fe/f apokAcs-h]的恒定年龄分布。椎间盘从内而外生长，在整个阶段的恒星形成速率中具有径向梯度。尽管径向依赖性，但我们模拟的光环中金属的流出衰减比显示了圆盘生长的时间无关的剖面缩放。模拟的圆盘经历了两种气体流入模式：（i）金属贫困和相对较低的插座 - [$α$/fe]气体，以及（ii）径向流量已经以化学增强的气体向内移动，平均速度为$ \ sim0.7 $ km/s。此外，我们发现恒星迁移主要发生在$ \ sim5 $ gyr的典型时间尺度上。我们预测的径向金属性梯度与脱哥式DR16的观察结果一致，而恒星迁移的主要影响是在斜坡中使用0.05 DEX/KPC将径向金属度谱弄平。我们还表明，迁移的效果在[$α$/fe]中比在薄盘恒星的[fe/h]年龄关系中更重要。
In order to understand the roles of metal flows in galaxy formation and evolution, we analyse our self-consistent cosmological chemo-dynamical simulation of a Milky Way like galaxy during its thin-disc phase. Our simulated galaxy disc qualitatively reproduces the variation of the dichotomy in [$α$/Fe]-[Fe/H] at different Galactocentric distances as derived by APOGEE-DR16, as well as the stellar age distribution in [$α$/Fe]-[Fe/H] from APOKASC-2. The disc grows from the inside out, with a radial gradient in the star-formation rate during the entire phase. Despite the radial dependence, the outflow-to-infall ratio of metals in our simulated halo shows a time-independent profile scaling with the disc growth. The simulated disc undergoes two modes of gas inflow: (i) an infall of metal-poor and relatively low-[$α$/Fe] gas, and (ii) a radial flow where already chemically-enriched gas moves inwards with an average velocity of $\sim0.7$ km/s. Moreover, we find that stellar migrations mostly happen outwards, on typical time scales of $\sim5$ Gyr. Our predicted radial metallicity gradients agree with the observations from APOGEE-DR16, and the main effect of stellar migrations is to flatten the radial metallicity profiles by 0.05 dex/kpc in the slopes. We also show that the effect of migrations can appear more important in [$α$/Fe] than in the [Fe/H]-age relation of thin-disc stars.
