THE PRIMORDIAL DEUTERIUM ABUNDANCE OF THE MOST METAL-POOR DAMPED Lyα SYSTEM
THE PRIMORDIAL DEUTERIUM ABUNDANCE OF THE MOST METAL-POOR DAMPED Lyα SYSTEM
复制标题
最贫金属阻尼 Lyα 系统的原始氘丰度
DOI：
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发表时间：
2016
期刊：
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通讯作者：
R. Jorgenson
中科院分区：
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作者：
R. Cooke;M. Pettini;K. Nollett;R. Jorgenson
我们报告了目前已知的最贫金属阻尼Lyα（DLA）系统的发现和分析，该系统还显示了中性氘的莱曼系列吸收线。该系统的平均[O/H]丰度为[O/H]=-2.804±0.015，其中包括[O/H]=-3.07±0.03的吸收分量。尽管不幸地混合了许多弱 Di 吸收线，但我们报告了该系统的氘丰度的精确测量。使用 DLA 中六种最高质量和自洽分析的 D/H 测量值，我们报告了 D/H 随着金属丰度的增加而略有下降的初步证据。这一趋势必须通过未来跨越一系列金属丰度的高精度 D/H 测量来证实。这六个独立测量值的加权平均值提供了我们对氘原始丰度的最佳估计，105 (D/H)P = 2.547 ± 0.033 ( )。我们对大爆炸核合成 (BBN) 进行了一系列详细的蒙特卡罗计算，其中结合了几个关键核反应截面的最新测定，并传播了它们相关的不确定性。如果我们采用最新的反应速率理论测定，则将 (D/H)P 测量与这些 BBN 计算相结合，可得出宇宙重子密度的估计值 100 ΩB,0 h2(BBN) = 2.156 ± 0.020。 ΩB,0 h2 的测量值与根据普朗克宇宙微波背景观测估计的标准模型值相差约 2.3σ。使用基于最佳可用实验横截面数据的反应速率，我们估计 100 ΩB,0 h2(BBN) = 2.260 ± 0.034，这与普朗克值更加一致。即将对关键横截面进行的测量可能会进一步阐明这种差异。
We report the discovery and analysis of the most metal-poor damped Lyα (DLA) system currently known, which also displays the Lyman series absorption lines of neutral deuterium. The average [O/H] abundance of this system is [O/H] = −2.804 ± 0.015, which includes an absorption component with [O/H] = −3.07 ± 0.03. Despite the unfortunate blending of many weak D i absorption lines, we report a precise measurement of the deuterium abundance of this system. Using the six highest-quality and self-consistently analyzed measures of D/H in DLAs, we report tentative evidence for a subtle decrease of D/H with increasing metallicity. This trend must be confirmed with future high-precision D/H measurements spanning a range of metallicity. A weighted mean of these six independent measures provides our best estimate of the primordial abundance of deuterium, 105 (D/H)P = 2.547 ± 0.033 ( ). We perform a series of detailed Monte Carlo calculations of Big Bang nucleosynthesis (BBN) that incorporate the latest determinations of several key nuclear reaction cross-sections, and propagate their associated uncertainty. Combining our measurement of (D/H)P with these BBN calculations yields an estimate of the cosmic baryon density, 100 ΩB,0 h2(BBN) = 2.156 ± 0.020, if we adopt the most recent theoretical determination of the reaction rate. This measure of ΩB,0 h2 differs by ∼2.3σ from the Standard Model value estimated from the Planck observations of the cosmic microwave background. Using instead a reaction rate that is based on the best available experimental cross-section data, we estimate 100 ΩB,0 h2(BBN) = 2.260 ± 0.034, which is in somewhat better agreement with the Planck value. Forthcoming measurements of the crucial cross-section may shed further light on this discrepancy.