The primordial deuterium abundance at z abs = 2.504 from a high signal-to-noise spectrum of Q1009+2956
The primordial deuterium abundance at z abs = 2.504 from a high signal-to-noise spectrum of Q1009+2956
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DOI：
10.1093/mnras/sty1003
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发表时间：
2017-06
影响因子：
4.8
通讯作者：
E. O. Zavarygin;J. Webb;V. Dumont;V. Dumont;S. Riemer-Sørensen;S. Riemer-Sørensen
中科院分区：
文献类型：
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作者：
E. O. Zavarygin;J. Webb;V. Dumont;V. Dumont;S. Riemer-Sørensen;S. Riemer-Sørensen
利用Keck望远镜对z(Em)=2.63类星体Q1009+2956的光谱进行了广泛的观测。莱曼极限吸收系统z(Abs)=2.504以前被Burles&Tytler使用信噪比(S/N)在z(Abs)=2.504的Lyα附近的连续体中大约每像素60的光谱来测量D/H。现在可用的更大的数据集结合在一起形成了非常高的S/N谱，大约每像素147。在这个莱曼极限系统中检测到了几条重元素吸收线，这对运动学结构提供了很强的约束。我们探索了一套吸收系统模型，发现来自低柱密度HI云的弱掺杂Lyα吸收很可能污染了氘的特征，降低了预期的D/H精度。我们得到该体系的D/H=2.48(-0.35)(+0.41)×10(-5)。将这一新的测量方法与文献中的其他测量方法相结合，并将最小修剪平方方法应用于15个D/H测量的统计样本，得到了一个由13个值组成的“可靠”样本。该样品的原始氚丰度为(D/H)(P)=(2.545+/-0.025)x 10(-5)。相应的宇宙平均重子密度为欧米伽(B)h(2)=0.02174+/-0.00025。类星体吸收数据与2015年CMB Planck(TT+低P+透镜)测量的精度相同，但略有不一致，欧米茄(B)h(2)=0.02226+/-0.00023。要确定这是否是随机波动，还需要更多类星体和更精确的核数据。
The spectrum of the z(em) = 2.63 quasar Q1009+2956 has been observed extensively on the Keck telescope. The Lyman limit absorption system z(abs) = 2.504 was previously used to measure D/H by Burles & Tytler using a spectrum with signal to noise (S/N) approximately 60 per pixel in the continuum near Ly alpha at z(abs) = 2.504. The larger data set now available combines to form an exceptionally high S/N spectrum, around 147 per pixel. Several heavy element absorption lines are detected in this Lyman limit system, providing strong constraints on the kinematic structure. We explore a suite of absorption system models and find that the deuterium feature is likely to be contaminated by weak interloping Ly alpha absorption from a low column density HI cloud, reducing the expected D/H precision. We find D/H = 2.48(-0.35)(+0.41) x 10(-5) for this system. Combining this new measurement with others from the literature and applying the method of Least Trimmed Squares to a statistical sample of 15 D/H measurements results in a 'reliable' sample of 13 values. This sample yields a primordial deuterium abundance of (D/H)(p) = (2.545 +/- 0.025) x 10(-5). The corresponding mean baryonic density of the Universe is Omega(b)h(2) = 0.02174 +/- 0.00025. The quasar absorption data are of the same precision as, and marginally inconsistent with, the 2015 CMB Planck (TT+lowP+lensing) measurement, Omega(b)h(2) = 0.02226 +/- 0.00023. Further quasar and more precise nuclear data are required to establish whether this is a random fluctuation.