论文标题
MWA II期的新EOR功率谱限制使用延迟谱法和新型系统排斥
New EoR Power Spectrum Limits From MWA Phase II Using the Delay Spectrum Method and Novel Systematic Rejection
论文作者
论文摘要
我们使用\ texttt {simpleds}延迟频谱管道对来自Murchison广场阵列的II阶段的回离数据时期的分析进行了分析。先前的工作分析了使用FHD/$ \ varepsilon $ ppsilon成像管道分析相同的观察结果，因此目前的分析代表了首次将两种主要类型的21 cm宇宙学功率谱估计方法应用于相同的数据集。我们对21厘米电源振幅的限制跨度为$ k $ | k |的范围。 <1〜h_ {100} {\ rm mpc}^{ - 1} $，最低测量值为$δ^2（k）\ leq $ $ $ $ 4.58 \ times10^3 $ mk $^2 $ at $ k = 0.190 H_ = 0.190 H_ {100} {100} \ rmpc \ rmpc {mpc} {Mpc}^$ Z = 7.14}为了达到这些限制，我们需要在数据集中减轻先前未知的共同模式系统。如果不考虑，此系统引入了一个总体\ emph {负}偏差，该偏差可以使前景污染的测量结果看起来像是21 cm信号振幅上的严格，噪声限制的约束。这种系统的识别强调了建模系统学的风险是对功率谱和``保守式''的积极贡献，将所有测量值解释为上限。
We present an analysis of Epoch of Reionization data from Phase II of the Murchison Widefield Array using the \texttt{simpleDS} delay spectrum pipeline. Prior work analyzed the same observations using the FHD/$\varepsilon$ppsilon 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 $|k| < 1~h_{100}{\rm Mpc}^{-1}$ with a lowest measurement of $Δ^2(k) \leq$ $4.58\times10^3$ mK$^2$ 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 \emph{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.
