Chasing the impact of the Gaia-Sausage-Enceladus merger on the formation of the Milky Way thick disc
Chasing the impact of the Gaia-Sausage-Enceladus merger on the formation of the Milky Way thick disc
复制标题
追踪盖亚-香肠-土卫二合并对银河系厚盘形成的影响
DOI：
10.1093/mnrasl/slad033
复制
发表时间：
2023
影响因子：
--
通讯作者：
Freeman Ken
中科院分区：
文献类型：
--
作者：
Ciuca Ioana;Kawata Daisuke;Ting Yuan-Sen;Grand Robert J J;Miglio Andrea;Hayden Michael;Baba Junichi;Fragkoudi Francesca;Monty Stephanie;Buder Sven;Freeman Ken
我们采用贝叶斯机器学习框架 BINGO（银河考古学贝叶斯推理）来获得斯隆数字巡天（APOGEE-2 高分辨率光谱巡天）第 17 次数据发布中存在的 68 360 颗红巨星和红丛星的高质量恒星年龄估计。通过检查银盘恒星的去噪年龄-金属丰度关系，我们发现早期时期金属丰度随着[Mg/Fe]的增加而下降，随后出现[Fe/H]增加和[Mg/Fe]减少的化学富集事件。这一结果与类银河系放大宇宙学模拟 Auriga 中发现的早期富含气体合并引起的化学演化一致。在 Auriga 18 合并的初始阶段，由于合并稀释了金属含量并且主星系的 [Mg/Fe] 增加，金属丰度下降。我们的研究结果表明，我们银河系的最后一次大规模合并，盖亚-香肠-土卫二，很可能是一次重要的富含气体合并，并引发了星暴，有助于早期时代厚盘中富含金属部分的化学富集和形成。
We employ our Bayesian Machine Learning framework BINGO (Bayesian INference for Galactic archaeOlogy) to obtain high-quality stellar age estimates for 68 360 red giant and red clump stars present in the 17thdata release of the Sloan Digital Sky Survey, the APOGEE-2 high-resolution spectroscopic survey. By examining the denoised age-metallicity relationship of the Galactic disc stars, we identify a drop in metallicity with an increase in [Mg/Fe] at an early epoch, followed by a chemical enrichment episode with increasing [Fe/H] and decreasing [Mg/Fe]. This result is congruent with the chemical evolution induced by an early-epoch gas-rich merger identified in the Milky Way-like zoom-in cosmological simulation Auriga. In the initial phase of the merger of Auriga 18 there is a drop in metallicity due to the merger diluting the metal content and an increase in the [Mg/Fe] of the primary galaxy. Our findings suggest that the last massive merger of our Galaxy, theGaia-Sausage-Enceladus, was likely a significant gas-rich merger and induced a starburst, contributing to the chemical enrichment and building of the metal-rich part of the thick disc at an early epoch.