论文标题
电离时代21-CM信号观察时期的校准要求-II。与时间相关的残余增长的偏差和差异的分析估计
Calibration requirements for Epoch of Reionization 21-cm signal observations -- II. Analytical estimation of the bias and variance with time-correlated residual gains
论文作者
论文摘要
从中性氢观察中性氢的红移21厘米信号是理解结构形成及其在电离和重新离子后时代的演变的关键。除了在观察到的频率范围内存在较大前景的数量级外，干涉仪与电离层效应结合的仪器效应在从强前景中提取21 cm信号方面带来了巨大的挑战。时间和频率相关的残余增益误差的系统效应源自测量过程，引入了偏差并增强了功率谱测量的方差。在这项工作中，我们研究了在有强的前景存在下时间相关的残余增益错误的效果。我们提出了一种产生功率谱中偏差和变化的分析估计的方法。我们使用模拟观察结果来确认此方法的功效，然后使用它来了解增益错误的各种影响。我们发现，随着残差增益误差的标准偏差增加，估计的偏差取代了方差。据观察，估计增益解决方案的最佳选择可以最大程度地减少风险。我们还发现，对于这些研究，具有较高基线密度的干涉仪是首选的仪器。
Observation of redshifted 21-cm signals from neutral hydrogen holds the key to understanding the structure formation and its evolution during the reionization and post-reionization era. Apart from the presence of orders of magnitude larger foregrounds in the observed frequency range, the instrumental effects of the interferometers combined with the ionospheric effects present a considerable challenge in the extraction of 21-cm signals from strong foregrounds. The systematic effects of time and frequency correlated residual gain errors originating from the measurement process introduce a bias and enhance the variance of the power spectrum measurements. In this work, we study the effect of time-correlated residual gain errors in the presence of strong foreground. We present a method to produce analytic estimates of the bias and vari ance in the power spectrum. We use simulated observations to confirm the efficacy of this method and then use it to understand various effects of the gain errors. We find that as the standard deviation in the residual gain errors increases, the bias in the estimation supersedes the variance. It is observed that an optimal choice of the time over which the gain solutions are estimated minimizes the risk. We also find that the interferometers with higher baseline densities are preferred instruments for these studies.
