从稀疏采样模式推断射电波束：以默奇森宽场阵列为例
Inferring radio beams from sparse sampling patterns: a case study with the Murchison Widefield Array
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中文总结 AI 辅助
本研究利用卫星观测和两种贝叶斯方法推断默奇森宽场阵列的137兆赫功率波束，揭示了零点偏移和旁瓣形变，证明了稀疏采样下波束重建的可行性。
中文摘要 AI 辅助
精确的主波束模型对于高动态范围的射电实验至关重要，特别是对于搜寻再电离纪元红移21厘米信号的实验，在这些实验中，波束误差可能将明亮的银河前景辐射耦合进微弱的宇宙学测量中。利用重新处理的卫星观测数据，我们推断出默奇森宽场阵列接收单元在137兆赫、指向天顶方向时的功率波束。我们开发了两种互补的贝叶斯方法，用于量化与标称电磁模拟的偏差：一种是对单个偶极子间复杂变化的物理驱动模型，另一种是用于灵活方向依赖结构的层次样条模型。测量结果显示，零点更浅且位置偏移，同时存在相干的旁瓣形变。偶极子模型捕捉了大部分这种宽泛结构，而样条模型则恢复了额外的局部特征，同时对孤立的通道形状伪影保持较强的鲁棒性。尽管四个独立的20天子集具有稀疏且不同的采样模式，每个子集包含全数据集的约20%，但它们在整个可见半球上恢复了一致的零点和旁瓣形态。这些结果表明，机会性卫星传输可以支持实用且可重复的波束重建，同时激励未来对完整琼斯响应的色度、相位参考测量。
英文摘要
Accurate primary-beam models are essential for high-dynamic-range radio experiments, particularly searches for the redshifted 21-cm signal from the Epoch of Reionisation, where beam errors can couple bright foreground emission into the faint cosmological measurement. Using reprocessed satellite observations we infer the 137-MHz, zenith-pointed power beams of Murchison Widefield Array receiving elements. We develop two complementary Bayesian approaches for quantifying departures from nominal electromagnetic simulations: a physically motivated model of complex variations among individual dipoles and a hierarchical spline model for flexible direction-dependent structure. The measurements reveal shallower and displaced nulls together with coherent sidelobe deformations. The dipole model captures much of this broad structure, whereas the spline recovers additional localised features while remaining largely robust to isolated pass-shaped artefacts. Despite their sparse and distinct sampling patterns, four independent 20-day subsets, each containing approximately 20\% of the full dataset, recover consistent null and sidelobe morphology across the visible hemisphere. These results demonstrate that opportunistic satellite transmissions can support practical, repeatable beam reconstruction, while motivating future chromatic, phase-referenced measurements of the full Jones response.
发表机构
- McGill University（麦吉尔大学）
- The University of Melbourne（墨尔本大学）
机构由 AI 辅助整理，请以论文原文为准。
