论文标题
银河系的集会历史有多不寻常？
How Unusual is the Milky Way's Assembly History?
论文作者
论文摘要
在$λ$ CDM结构形成模型中，银河光环是通过质量和较小亚基的合并而建立的。银河系（MW）Halo经历的最新大规模合并活动是大麦芽云的积聚（LMC；其恒星质量为$ \ sim \; 10^9m_ \ odot $）。最近对来自\ textit {gaia}卫星的银河恒星数据的分析发现了较早的大型积聚事件，即Gaia-cenceladus-sausage（GES），该事件与MW大约10 Gyr合并。在这里，我们使用Eagle宇宙流体动力学模拟来研究模拟的MW质量光环的特性，以具有与MW相似的积聚历史，特别是最近在GES合并和sim sim sim sim sim sim sems sim sems sim ers sim sems sim sems sim ers sim ers sim sems（$ se wer）之间的“ LMC”星系和“ GES”合并时（ 16 $ \ sim的$ \ sim;星系自然最终以$ z = 0 $的颜色磁性图中的“蓝色云”最终出现，往往具有圆盘形态，并且具有大于平均值的卫星星系数量。
In the $Λ$CDM model of structure formation galactic haloes build up by accretion of mass and mergers of smaller subunits. The most recent massive merger event experienced by the Milky Way (MW) halo was the accretion of the Large Magellanic Cloud (LMC; which has a stellar mass of $\sim \; 10^9M_\odot$). Recent analyses of galactic stellar data from the \textit{Gaia} satellite have uncovered an earlier massive accretion event, the Gaia-Enceladus-Sausage (GES), which merged with the MW around 10 Gyr ago. Here, we use the EAGLE cosmological hydrodynamics simulation to study properties of simulated MW-mass haloes constrained to have accretion histories similar to that of the MW, specifically the recent accretion of an "LMC" galaxy and a "GES'' merger, with a quiescent period between the GES merger and the infall of the LMC (the "GES \& LMC" class). We find that $\sim 16$ per cent of MW-mass haloes have an LMC; $\sim 5$ per cent have a GES event and no further merger with an equally massive object since $z=1$; and only $0.65$ per cent belong to the LMC \& GES category. The progenitors of the MWs in this last category are much less massive than average at early times but eventually catch up with the mean. The LMC \& GES class of galaxies naturally end up in the "blue cloud" in the colour-magnitude diagram at $z=0$, tend to have a disc morphology and have a larger than average number of satellite galaxies.
