标题： 向超贫金属DLAs迈进：将最贫金属DLA的化学与第一代恒星联系起来 显示英文标题

标题： Towards ultra metal-poor DLAs: linking the chemistry of the most metal-poor DLA to the first stars

摘要： 我们提供了目前已知最贫金属的矮化莱曼-α（DLA）系统的凯克/HIRES数据。通过针对最强可访问的Fe II特征，我们将[Fe/H]丰度测定的上限提高了约1 dex，发现[Fe/H] < -3.66（2 sigma）。我们还为此系统提供了对奇原子序数元素相对丰度的第一个上限 [Al/H] < -3.82（2 sigma）。因此，我们的分析确认了这个z_abs=3.07 DLA不仅是目前已知最贫金属的DLA，也是最贫铁的DLA。我们利用这个DLA的化学组成，并结合随机化学富集模型，研究其富集历史。我们发现，这个DLA最好由单个第三星族前体的产出模型来描述，而不是多个第三星族恒星。然后，我们将其与其他遗迹环境进行比较，特别是邻近超微弱矮星系中的恒星。我们在Bootes I中识别出一颗恒星，其化学组成与这里提供的DLA相似，表明它可能诞生于具有相似特性的气体云中。红移z_abs=3.07的极端贫金属DLA（即大爆炸后约2 Gyrs）可能存在于早期宇宙中最少污染的环境中。 显示英文摘要

摘要： We present new Keck/HIRES data of the most metal-poor damped Lyman-alpha (DLA) system currently known. By targeting the strongest accessible Fe II features, we have improved the upper limit of the [Fe/H] abundance determination by ~1 dex, finding [Fe/H]<-3.66 (2 sigma). We also provide the first upper limit on the relative abundance of an odd-atomic number element for this system [Al/H]<-3.82 (2 sigma). Our analysis thus confirms that this z_abs=3.07 DLA is not only the most metal-poor DLA but also the most iron-poor DLA currently known. We use the chemistry of this DLA, combined with a stochastic chemical enrichment model, to probe its enrichment history. We find that this DLA is best modelled by the yields of an individual Population III progenitor rather than multiple Population III stars. We then draw comparisons with other relic environments and, particularly, the stars within nearby ultra-faint dwarf galaxies. We identify a star within Bootes I, with a similar chemistry to that of the DLA presented here, suggesting that it may have been born in a gas cloud that had similar properties. The extremely metal-poor DLA at redshift z_abs=3.07 (i.e. ~2 Gyrs after the Big Bang) may reside in one of the least polluted environments in the early Universe.