New EoR power spectrum limits from MWA Phase II using the delay spectrum method and novel systematic rejection
New EoR power spectrum limits from MWA Phase II using the delay spectrum method and novel systematic rejection
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DOI：
10.1093/mnras/stad845
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发表时间：
2022-10
影响因子：
4.8
通讯作者：
M. Kolopanis;J. Pober;D. Jacobs;Samantha McGraw
中科院分区：
文献类型：
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作者：
M. Kolopanis;J. Pober;D. Jacobs;Samantha McGraw
我们提出了一个分析的时代的再电离数据从第二阶段的默奇森宽场阵列使用simpleDS延迟谱管道。先前的工作分析了相同的观测使用FHD/PIPPPLEM成像管道，因此，本分析代表了第一次，这两种主要类型的21厘米宇宙学功率谱估计方法已被应用于同一数据集。我们对21 cm功率谱振幅的限制跨越k空间中的范围：|K| < 1 h100 Mpc−1，最低测量值Δ2（k）≤ 4.58 × 103 mK2，$k = 0.190\，h_{100}\，\rm {Mpc}^{-1}$，z = 7.14。为了达到这些限制，我们需要减轻数据集中先前未识别的共模系统。如果不考虑，则该系统引入了总体负偏差，其可以使前景污染测量表现为对21 cm信号幅度的严格的噪声限制约束。该系统的识别突出了系统学建模的风险，作为对功率谱的肯定贡献，并将所有测量值“保守地”解释为上限。
We present an analysis of Epoch of Reionization data from Phase II of the Murchison Widefield Array using the simpleDS delay spectrum pipeline. Prior work analyzed the same observations using the FHD/ϵppsilon imaging pipeline, and so the present analysis represents the first time that both principal types of 21 cm cosmology power spectrum estimation approaches have been applied to the same data set. Our limits on the 21 cm power spectrum amplitude span a range in k space of |k| < 1 h100 Mpc−1 with a lowest measurement of Δ2(k) ≤ 4.58 × 103 mK2 at $k = 0.190\, h_{100}\, \rm {Mpc}^{-1}$ and z = 7.14. In order to achieve these limits, we need to mitigate a previously unidentified common mode systematic in the data set. If not accounted for, this systematic introduces an overall negative bias that can make foreground contaminated measurements appear as stringent, noise-limited constraints on the 21 cm signal amplitude. The identification of this systematic highlights the risk in modeling systematics as positive-definite contributions to the power spectrum and in ‘conservatively’ interpreting all measurements as upper limits.