Bayesian constraints on the global 21-cm signal from the Cosmic Dawn
Bayesian constraints on the global 21-cm signal from the Cosmic Dawn
复制标题
来自宇宙黎明的全球 21 厘米信号的贝叶斯约束
DOI：
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发表时间：
2016
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通讯作者：
F. Schinzel
中科院分区：
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作者：
G. Bernardi;G. Bernardi;J. Zwart;J. Zwart;Danny C. Price;L. J. Greenhill;A. Mesinger;J. Dowell;T. Eftekhari;Steven W. Ellingson;J. Kocz;F. Schinzel
第一个光源的诞生和随后的再电离时代最好通过21厘米的红移发射线来研究，这是前两个光源的印记。在这项工作中，我们提出了一种全贝叶斯方法HIBAYES，用于从更亮的前景发射中提取微弱的全球（天空平均）21厘米信号。我们展示了一个简化的（但合理的）高斯模型，宇宙黎明时期21厘米的发射(15。z。30)，由振幅dehi、频率峰值HI和宽度HI参数化，即使在存在结构化前景频谱（参数化为7阶多项式）的情况下，只要提供足够的信噪比（单偶极子观测400小时），也可以提取。我们将我们的方法应用于大孔径实验的早期19分钟长的观测，以探测黑暗时代，将21厘米的信号幅度和宽度分别限制为890 6:5 MHz（对应于红移z ' 20时的z > 1:9），在95%的置信水平范围内13:2 > 50 MHz)。
The birth of the first luminous sources and the ensuing epoch of reionization are best studied via the redshifted 21-cm emission line, the signature of the first two imprinting the last. In this work we present a fully-Bayesian method, HIBAYES, for extracting the faint, global (sky-averaged) 21-cm signal from the much brighter foreground emission. We show that a simplified (but plausible), Gaussian model of the 21-cm emission from the Cosmic Dawn epoch (15 . z . 30), parameterized by an amplitudeAHI, a frequency peak HI and a width HI, can be extracted even in the presence of a structured foreground frequency spectrum (parameterized as a 7 th -order polynomial), provided sufficient signal-to-noise (400 hours of observation with a single dipole). We apply our method to an early, 19-minute long observation from the Large aperture Experiment to detect the Dark Ages, constraining the 21-cm signal amplitude and width to be 890 6:5 MHz (corresponding to z > 1:9 at redshift z’ 20) respectively at the 95-per-cent confidence level in the range 13:2 > 50 MHz).