The existence of a radio synchrotron background (RSB) excess is implied by a number of measurements, including excess emission seen by the ARCADE 2 and LWA experiments. Highly sensitive wideband radio arrays, of the kind used to measure the cosmic 21cm signal, provide a promising way to further constrain the RSB excess through its anisotropy, providing additional insight into its origin. We present a framework for evaluating the potential of 21cm arrays to disentangle different components of the diffuse radio sky based on the combination of their frequency spectrum and angular power spectrum (APS). The formalism is designed to calculate uncertainties due to the intrinsic cosmic variance alone or together with instrumental noise. In particular, we predict the potential for measuring the anisotropy of a broad generalised class of excess radio background models using the low-frequency HERA array as an example. We find that a HERA-like array can distinguish an RSB excess from other sky components based on its angular clustering and spectral dependence, even if these are quite similar to one or more of the other components – but only in the case that the RSB excess is relatively bright.

中文翻译：

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解开各向异性射电天空：Fisher 对 21 厘米阵列的预测

许多测量结果表明存在无线电同步加速器背景 (RSB) 过量，包括 ARCADE 2 和 LWA 实验中观察到的过量发射。用于测量宇宙 21 厘米信号的高灵敏度宽带无线电阵列提供了一种有希望的方法，通过其各向异性进一步限制 RSB 过量，从而提供对其起源的更多了解。我们提出了一个框架，用于评估 21 厘米阵列基于频谱和角功率谱 (APS) 的组合来解开漫射射电天空的不同组成部分的潜力。该形式旨在计算由于单独的内在宇宙方差或与仪器噪声一起引起的不确定性。特别是，我们以低频 HERA 阵列为例，预测了测量广泛广义类别的过量无线电背景模型各向异性的潜力。我们发现，类 HERA 阵列可以根据其角度聚类和光谱依赖性将 RSB 过量与其他天空分量区分开来，即使这些分量与一个或多个其他分量非常相似，但前提是 RSB 过量是比较亮的。