论文标题
串联冗余/基于天空的校准在MWA II期数据分析中的影响
The Impact of Tandem Redundant/Sky-Based Calibration in MWA Phase II Data Analysis
论文作者
论文摘要
精确的仪器校准对于21 cm宇宙学实验至关重要。 Murchison Widefield阵列(MWA)II期紧凑型配置为我们提供了冗余校准和基于天空的校准算法的机会;使用两者串联是一种潜在的方法来减轻由不准确的天空模型引起的校准误差。 MWA电离时期(EOR)实验靶向具有深入观察的三个天空(称为EOR0,EOR1和EOR2)的斑块。 \ cite {li_2018}和\ cite {wenyang_2019}的先前工作研究了串联校准对EOR0字段的影响,发现单独的基于天空校准的功率谱没有显着改善。在这项工作中,我们将类似的技术应用于EOR1字段,并找到一个明显的结果:串联校准的功率谱的改进非常重要。为了理解这一结果,我们分析了校准解决方案本身以及对EOR1观测的三晚对功率谱的影响。我们得出的结论是,eOR1中明亮的射电星系fornax a的存在降低了基于天空的校准的性能,这又使冗余校准具有更大的影响。这些结果表明,冗余校准确实可以减轻某种级别的模型分组误差。
Precise instrumental calibration is of crucial importance to 21-cm cosmology experiments. The Murchison Widefield Array's (MWA) Phase II compact configuration offers us opportunities for both redundant calibration and sky-based calibration algorithms; using the two in tandem is a potential approach to mitigate calibration errors caused by inaccurate sky models. The MWA Epoch of Reionization (EoR) experiment targets three patches of the sky (dubbed EoR0, EoR1, and EoR2) with deep observations. Previous work in \cite{Li_2018} and \cite{Wenyang_2019} studied the effect of tandem calibration on the EoR0 field and found that it yielded no significant improvement in the power spectrum over sky-based calibration alone. In this work, we apply similar techniques to the EoR1 field and find a distinct result: the improvements in the power spectrum from tandem calibration are significant. To understand this result, we analyze both the calibration solutions themselves and the effects on the power spectrum over three nights of EoR1 observations. We conclude that the presence of the bright radio galaxy Fornax A in EoR1 degrades the performance of sky-based calibration, which in turn enables redundant calibration to have a larger impact. These results suggest that redundant calibration can indeed mitigate some level of model-incompleteness error.