我们目前的测量碳，氧，硅，铁在类星体吸收系统存在时，宇宙大约是10亿岁。我们使用Keck，Magellan和VLT光学和近红外光谱测量了9个低电离系统中4.7 < z < 6.3的柱密度，具有中等到高分辨率。C II、O I、Si II和Fe II之间的柱密度比在较低的红移处与亚DLA和贫金属（[M/H] < -1）DLA几乎相同，在2 < z < 6上没有显著的演变。任何两个元素的比率的估计固有散射也很小，具有典型的r.m.s. 4.7系统的偏差<0.1 dex. These facts suggest that dust depletion and ionization effects are minimal in our z >，在较低的红移的DLAs，和柱密度比接近固有的相对元素丰度。因此，我们的z > 4.7系统中的丰度可能代表宇宙历史第一个千兆年内恒星星族的典型综合产额。由于在这些红移的宇宙年龄所施加的时间限制，我们的测量因此直接限制了大质量恒星的金属生产，包括瞬发超新星的铁产量。红移演化的缺乏进一步表明，在z > 2时，大多数贫金属吸收系统的金属库存也由大质量恒星主导，延迟的Ia型超新星或AGB风的贡献很小。我们系统中的相对丰度与金属含量非常低、非碳增强的星系晕恒星中的相对丰度大致一致。这与现今贫金属恒星可能早在大爆炸后10亿年就形成的观点一致。
英文摘要：
We present measurements of carbon, oxygen, silicon, and iron in quasar absorption systems existing when the universe was roughly one billion years old. We measure column densities in nine low-ionization systems at 4.7 < z < 6.3 using Keck, Magellan, and VLT optical and near-infrared spectra with moderate to high resolution. The column density ratios among C II, O I, Si II, and Fe II are nearly identical to sub-DLAs and metal-poor ([M/H] < -1) DLAs at lower redshifts, with no significant evolution over 2 < z < 6. The estimated intrinsic scatter in the ratio of any two elements is also small, with a typical r.m.s. deviation of <0.1 dex. These facts suggest that dust depletion and ionization effects are minimal in our z > 4.7 systems, as in the lower-redshift DLAs, and that the column density ratios are close to the intrinsic relative element abundances. The abundances in our z > 4.7 systems are therefore likely to represent the typical integrated yields from stellar populations within the first gigayear of cosmic history. Due to the time limit imposed by the age of the universe at these redshifts, our measurements thus place direct constraints on the metal production of massive stars, including iron yields of prompt supernovae. The lack of redshift evolution further suggests that the metal inventories of most metal-poor absorption systems at z > 2 are also dominated by massive stars, with minimal contributions from delayed Type Ia supernovae or AGB winds. The relative abundances in our systems broadly agree with those in very metal-poor, non-carbon-enhanced Galactic halo stars. This is consistent with the picture in which present-day metal-poor stars were potentially formed as early as one billion years after the Big Bang.
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