THE IMPACT OF POINT-SOURCE SUBTRACTION RESIDUALS ON 21 cm EPOCH OF REIONIZATION ESTIMATION
THE IMPACT OF POINT-SOURCE SUBTRACTION RESIDUALS ON 21 cm EPOCH OF REIONIZATION ESTIMATION
复制标题
点源减法残差对21 cm再电离估计的影响
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
S. Tingay
中科院分区：
文献类型：
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作者：
C. Trott;R. Wayth;S. Tingay
前景源的精确相减对于探测和估计来自再电离时期（EoR）的21 cm H i信号是至关重要的。我们量化了由于测量数据集的限制而导致的不完美的点源减法如何在数据集中产生结构化的残差信号。我们使用的克拉美-拉奥下限，作为一个度量，用于量化的精度与参数可以被测量，估计由于不完美的点源减法在可见性数据集中的残留信号。然后，我们传播这些残差到两个指标的兴趣为21厘米EoR实验的角功率谱和二维功率谱，使用全解析协变推导，解析变推导和协变蒙特卡罗模拟的组合。这种方法与以前的工作有两个不同之处：（1）它使用信息论来设置点源位置误差，而不是假设全局均方根误差;（2）它描述了一种分析传播误差的方法，从而获得功率谱的完整相关结构。该方法适用于两个即将推出的低频仪器，建议进行统计EoR实验：默奇森宽场阵列和精密阵列探测时代的再电离。除了实际的天线配置，我们适用于最小冗余和最大冗余配置的方法。我们发现，剥离源1 Jy以上，残留信号的幅度，其方差，将小于从热噪声的贡献，为即将到来的EoR实验提出的观测参数，和最佳减法的亮点源将不会是一个限制因素EoR参数估计。然后，我们使用的形式主义，提供一个从头分析推导激励的“楔形”功能的二维功率谱，补充文献中以前的讨论。
Precise subtraction of foreground sources is crucial for detecting and estimating 21 cm H i signals from the Epoch of Reionization (EoR). We quantify how imperfect point-source subtraction due to limitations of the measurement data set yields structured residual signal in the data set. We use the Cramer–Rao lower bound, as a metric for quantifying the precision with which a parameter may be measured, to estimate the residual signal in a visibility data set due to imperfect point-source subtraction. We then propagate these residuals into two metrics of interest for 21 cm EoR experiments—the angular power spectrum and two-dimensional power spectrum—using a combination of full analytic covariant derivation, analytic variant derivation, and covariant Monte Carlo simulations. This methodology differs from previous work in two ways: (1) it uses information theory to set the point-source position error, rather than assuming a global rms error, and (2) it describes a method for propagating the errors analytically, thereby obtaining the full correlation structure of the power spectra. The methods are applied to two upcoming low-frequency instruments that are proposing to perform statistical EoR experiments: the Murchison Widefield Array and the Precision Array for Probing the Epoch of Reionization. In addition to the actual antenna configurations, we apply the methods to minimally redundant and maximally redundant configurations. We find that for peeling sources above 1 Jy, the amplitude of the residual signal, and its variance, will be smaller than the contribution from thermal noise for the observing parameters proposed for upcoming EoR experiments, and that optimal subtraction of bright point sources will not be a limiting factor for EoR parameter estimation. We then use the formalism to provide an ab initio analytic derivation motivating the “wedge” feature in the two-dimensional power spectrum, complementing previous discussion in the literature.
影响因子：
8.7
作者：
Komatsu, E.;Smith, K. M.;Wright, E. L.
通讯作者：
Wright, E. L.