论文标题
近原始气体的12C/13C比率与浓缩咖啡的限制
A bound on the 12C/13C ratio in near-pristine gas with ESPRESSO
论文作者
论文摘要
使用在4UT模式下在非常大的望远镜（VLT）上用浓缩咖啡获得的科学验证观测值，我们报告了第一个绑定在碳同位素比12c/13c上的静态，近乎原始阻尼的Ly-Alpha（DLA）系统的第一个结合，Z = 2.34。我们恢复限制log10（12c/13c）> +0.37（2 Sigma）。我们使用此DLA的丰度模式，再加上随机化学富集模型，推断出丰富的恒星的性能，发现该系统的总气体质量为log10（m_gas/m_sun）= 6.3+1.4-0.9，总体恒星质量为log10（m_**/m_sun）= 4.8+/-1.3。当前的观察结果是由质量<2.4 msun的金属贫困渐近巨型分支（AGB）恒星散发出浓度的，这限制了该DLA形成大多数富集恒星的时期。我们的建模表明，该DLA形成很少的恒星，直到氢气的宇宙电离后> 1 Gyr，尽管其金属性非常低（太阳能的〜1/1000），但该DLA在过去几百MYR中似乎已经形成了大多数恒星。将推断的恒星形成史与证据相结合，表明在红移z <3时，一些最贫穷的DLA显示出升高的[c/o]比率，我们建议可能受到非常金属贫困的DLA的影响，可能受到了电动淬火的影响。最后，鉴于与此处研究的DLA相关的吸收特征的简单性和静止，我们使用这些意式浓缩咖啡数据对细胞结构常数的可能变异性（Delta alpha/alpha =（ - 1.2 +/- 1.1）X10 X10^-5放置在可能的变化上。
Using science verification observations obtained with ESPRESSO at the Very Large Telescope (VLT) in 4UT mode, we report the first bound on the carbon isotope ratio 12C/13C of a quiescent, near-pristine damped Ly-alpha (DLA) system at z=2.34. We recover a limit log10(12C/13C) > +0.37 (2 sigma). We use the abundance pattern of this DLA, combined with a stochastic chemical enrichment model, to infer the properties of the enriching stars, finding the total gas mass of this system to be log10(M_gas/M_sun)=6.3+1.4-0.9 and the total stellar mass to be log10(M_*/M_sun)=4.8+/-1.3. The current observations disfavour enrichment by metal-poor Asymptotic Giant Branch (AGB) stars with masses <2.4 Msun, limiting the epoch at which this DLA formed most of its enriching stars. Our modelling suggests that this DLA formed very few stars until >1 Gyr after the cosmic reionization of hydrogen and, despite its very low metallicity (~1/1000 of solar), this DLA appears to have formed most of its stars in the past few hundred Myr. Combining the inferred star formation history with evidence that some of the most metal-poor DLAs display an elevated [C/O] ratio at redshift z<3, we suggest that very metal-poor DLAs may have been affected by reionization quenching. Finally, given the simplicity and quiescence of the absorption features associated with the DLA studied here, we use these ESPRESSO data to place a bound on the possible variability of the fine-structure constant, Delta alpha/alpha=(-1.2 +/- 1.1)x10^-5.
