A New Precision Measurement of the Small-scale Line-of-sight Power Spectrum of the Lyα Forest
A New Precision Measurement of the Small-scale Line-of-sight Power Spectrum of the Lyα Forest
复制标题
Lyα森林小尺度视距功率谱的新精确测量
DOI：
10.3847/1538-4357/aa9c81
复制
发表时间：
2017
期刊：
影响因子：
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通讯作者：
J. O’Meara
中科院分区：
文献类型：
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作者：
M. Walther;J. Hennawi;Hector Hiss;J. Oñorbe;K. Lee;Alberto Rorai;J. O’Meara
利用74 Keck/HIRES和VLT/UVES高分辨率、高信噪比的类星体谱，对Lyα森林1.8 < z < 3.4的功率谱进行了新的测量。我们开发了一个定制的管道来测量功率谱及其不确定性，它充分考虑了有限的分辨率和噪声，并校正了掩蔽缺失数据、阻尼Lyα吸收系统和金属吸收线引起的偏差。我们的测量结果在小尺度模式，无法访问以前的SDSS/BOSS分析前所未有的精度。众所周知，这些高k模对星系际介质的热状态非常敏感，但窄金属线的污染是一个重要的问题。我们量化了金属对小尺度功率的影响，并发现了对模式的适度影响。因此，通过掩蔽金属和限制，它们的影响被完全减轻。我们提出了一个端到端的贝叶斯前向建模框架，其中与我们的数据相同的噪声，分辨率和掩蔽的模拟光谱从Lyα森林模拟生成。这些模拟光谱用于构建自定义仿真器，使我们能够在稀疏网格模型之间进行插值，并执行马尔可夫链蒙特卡罗拟合。我们的结果同意以及BOSS的规模，测量重叠。BOSS的100级低k精度与我们的5%-15%高k测量相结合，产生了一个强大的新数据集，用于精确约束星系际介质的热历史，宇宙学参数和暗物质的性质。功率谱及其协方差矩阵以电子表格形式提供。
We present a new measurement of the Lyα forest power spectrum at 1.8 < z < 3.4 using 74 Keck/HIRES and VLT/UVES high-resolution, high-signal-to-noise-ratio quasar spectra. We developed a custom pipeline to measure the power spectrum and its uncertainty, which fully accounts for finite resolution and noise and corrects for the bias induced by masking missing data, damped Lyα absorption systems, and metal absorption lines. Our measurement results in unprecedented precision on the small-scale modes , inaccessible to previous SDSS/BOSS analyses. It is well known that these high-k modes are highly sensitive to the thermal state of the intergalactic medium, but contamination by narrow metal lines is a significant concern. We quantify the effect of metals on the small-scale power and find a modest effect on modes with . As a result, by masking metals and restricting to , their impact is completely mitigated. We present an end-to-end Bayesian forward-modeling framework whereby mock spectra with the same noise, resolution, and masking as our data are generated from Lyα forest simulations. These mock spectra are used to build a custom emulator, enabling us to interpolate between a sparse grid of models and perform Markov chain Monte Carlo fits. Our results agree well with BOSS on scales , where the measurements overlap. The combination of the percent-level low-k precision of BOSS with our 5%–15% high-k measurements results in a powerful new data set for precisely constraining the thermal history of the intergalactic medium, cosmological parameters, and the nature of dark matter. The power spectra and their covariance matrices are provided as electronic tables.