Measuring the Density Fields around Bright Quasars at z ∼ 6 with XQR-30 Spectra
Measuring the Density Fields around Bright Quasars at z ∼ 6 with XQR-30 Spectra
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DOI：
10.3847/1538-4357/ac658d
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发表时间：
2021-10
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通讯作者：
Huanqing Chen;A. Eilers;S. Bosman;N. Gnedin;Xiaohui Fan;Feige Wang;Jinyi Yang;V. D’Odorico;G. Becker;M. Bischetti;C. Mazzucchelli;A. Mesinger;A. Pallottini
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作者：
Huanqing Chen;A. Eilers;S. Bosman;N. Gnedin;Xiaohui Fan;Feige Wang;Jinyi Yang;V. D’Odorico;G. Becker;M. Bischetti;C. Mazzucchelli;A. Mesinger;A. Pallottini
在再电离时代使用类星体视线测量星际介质的密度是具有挑战性的，因为Lyα吸收是饱和的。然而，在发光类星体附近，增强的辐射在类星体光谱中创建了一个可观察到的邻近区域，其中Lyα吸收并未饱和。在这项研究中，我们使用来自扩展的XQR-30样品的10个高分辨率(R≳10,000)z∼6类星体光谱来测量类星体邻近区的密度场。我们在距离类星体3pppc的范围内发现了各种各样的环境。我们将观测到的密度累积分布函数(CDF)与计算机模拟的宇宙电离模型进行了比较，发现类星体的密度累积分布函数(CDF)在1.5到3pMpc之间有很好的一致性。这个区域距离类星体主机很远，因此接近宇宙的平均密度，这使得我们可以使用CDF来限制宇宙学参数σ8=0.6±0.3。这种不确定性主要是由于目前可用的高质量类星体视线数量有限。利用z≳6上已知的200多个类星体，这种方法将允许我们在未来将对σ8的约束收紧到百分比水平。在1.5pMpc以内靠近类星体的区域，我们发现密度比模拟中预测的高了1.23±0.17，这表明在z−6时明亮类星体(M1450和lt；Lt；∼26.5)的典型宿主暗物质晕质量为log10(Mh/M⊙)=12.5−0.7+0.4。
Measuring the density of the intergalactic medium using quasar sight lines in the epoch of reionization is challenging due to the saturation of Lyα absorption. Near a luminous quasar, however, the enhanced radiation creates a proximity zone observable in the quasar spectra where the Lyα absorption is not saturated. In this study, we use 10 high-resolution (R ≳ 10,000) z ∼ 6 quasar spectra from the extended XQR-30 sample to measure the density field in the quasar proximity zones. We find a variety of environments within 3 pMpc distance from the quasars. We compare the observed density cumulative distribution function (CDF) with models from the Cosmic Reionization on Computers simulation and find a good agreement between 1.5 and 3 pMpc from the quasar. This region is far away from the quasar hosts and hence approaching the mean density of the universe, which allows us to use the CDF to set constraints on the cosmological parameter σ 8 = 0.6 ± 0.3. The uncertainty is mainly due to the limited number of high-quality quasar sight lines currently available. Utilizing the more than 200 known quasars at z ≳ 6, this method will allow us to tighten the constraint on σ 8 to the percent level in the future. In the region closer to the quasar within 1.5 pMpc, we find that the density is higher than predicted in the simulation by 1.23 ± 0.17, suggesting that the typical host dark matter halo mass of a bright quasar (M 1450 < −26.5) at z ∼ 6 is log10(Mh/M⊙)=12.5−0.7+0.4 .