Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy
Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy
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DOI：
10.1093/mnras/staa2987
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发表时间：
2020-07
影响因子：
4.8
通讯作者：
D. Horta;R. Schiavon;J. Mackereth;J. Pfeffer;Andrew C. Mason;Shobhit Kisku;F. Fragkoudi;C. Allen
中科院分区：
文献类型：
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作者：
D. Horta;R. Schiavon;J. Mackereth;J. Pfeffer;Andrew C. Mason;Shobhit Kisku;F. Fragkoudi;C. Allen
我们报告的证据，从APOGEE的存在一个新的金属贫恒星结构位于银河系中心的104 kpc。这种新的星系内部结构（IGS）的特征是化学成分类似于银河系低质量卫星的化学成分，似乎是从化学和动力学上与银河系内部更富含金属的种群分离的。我们推测，这种结构与可能发生在银河系早期生命中的吸积事件有关。将这个结构的平均元素丰度与宇宙学数值模拟的预测进行比较，我们估计这个祖先系统的恒星质量为105 × 108 M <$，大约是最近发现的盖亚-土卫二/香肠系统质量的两倍。我们发现，在我们的贫金属（[Fe/H] < -0.8）的膨胀样品中，吸积：原位比率介于1：3和1：2之间，证实了各个团体的宇宙学数值模拟的预测。
We report evidence from APOGEE for the presence of a new metal-poor stellar structure located within ∼4 kpc of the Galactic Centre. Characterized by a chemical composition resembling those of low-mass satellites of the Milky Way, this new inner Galaxy structure (IGS) seems to be chemically and dynamically detached from more metal-rich populations in the inner Galaxy. We conjecture that this structure is associated with an accretion event that likely occurred in the early life of the Milky Way. Comparing the mean elemental abundances of this structure with predictions from cosmological numerical simulations, we estimate that the progenitor system had a stellar mass of ∼5 × 108 M⊙, or approximately twice the mass of the recently discovered Gaia-Enceladus/Sausage system. We find that the accreted:in situ ratio within our metal-poor ([Fe/H] < –0.8) bulge sample is somewhere between 1:3 and 1:2, confirming predictions of cosmological numerical simulations by various groups.