A Bayesian approach to modelling spectrometer data chromaticity corrected using beam factors – I. Mathematical formalism
A Bayesian approach to modelling spectrometer data chromaticity corrected using beam factors – I. Mathematical formalism
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使用光束因子校正光谱仪数据色度的贝叶斯方法 – I. 数学形式
DOI：
10.1093/mnras/stad610
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发表时间：
2023
影响因子：
4.8
通讯作者：
Vydula, Akshatha K.
中科院分区：
文献类型：
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作者：
Sims, Peter H.;Bowman, Judd D.;Mahesh, Nivedita;Murray, Steven G.;Barrett, John P.;Cappallo, Rigel;Monsalve, Raul A.;Rogers, Alan E. E.;Samson, Titu;Vydula, Akshatha K.
在与21厘米信号检测相关的尺度上准确解释仪器色度引起的光谱仪数据中的光谱结构是全球21厘米信号分析中最重大的挑战之一。在公开可用的探测全球再电离时期的实验中，使用基于光束因子的色度校正（BFCC）抑制了这种复杂的结构，该校正通过将数据除以仪器光束光谱结构的天空图加权模型来工作。对这些数据的一些分析采用了一些模型，这些模型首先假设这种校正是完全的。然而，尽管BFCC减轻了仪器色度对数据的影响，但考虑到关于前景光谱结构的现实假设，校正只是部分的。这使得解释与内在天空模型（假设对数据的光谱结构没有仪器贡献的模型）的数据的拟合变得复杂。在本文中，我们推导出一个BFCC数据模型从BFCC的分析处理，并证明使用模拟观测，在对比使用固有的天空模型的数据，BFCC数据模型，使无偏恢复的模拟全球21厘米的信号，从光束因子色度校正的数据的限制，数据与无误差的光束因子模型校正。
Accurately accounting for spectral structure in spectrometer data induced by instrumental chromaticity on scales relevant for detection of the 21-cm signal is among the most significant challenges in global 21-cm signal analysis. In the publicly available Experiment to Detect the Global Epoch of Reionization Signature low-band data set, this complicating structure is suppressed using beam-factor-based chromaticity correction (BFCC), which works by dividing the data by a sky-map-weighted model of the spectral structure of the instrument beam. Several analyses of these data have employed models that start with the assumption that this correction is complete. However, while BFCC mitigates the impact of instrumental chromaticity on the data, given realistic assumptions regarding the spectral structure of the foregrounds, the correction is only partial. This complicates the interpretation of fits to the data with intrinsic sky models (models that assume no instrumental contribution to the spectral structure of the data). In this paper, we derive a BFCC data model from an analytical treatment of BFCC and demonstrate using simulated observations that, in contrast to using an intrinsic sky model for the data, the BFCC data model enables unbiased recovery of a simulated global 21-cm signal from beam-factor chromaticity-corrected data in the limit that the data are corrected with an error-free beam-factor model.