利用广义条纹率滤波器优化光束整形
Optimized Beam Sculpting with Generalized Fringe-Rate Filters
摘要：
我们推广的条纹率滤波技术，从而由无线电干涉仪测量的vibrations重新加权根据其时间变化。随着地球的旋转，射电源以取决于它们在天空中的位置的速率穿过干涉仪的条纹图案。利用这种几何解释的条纹率，我们采用时域卷积内核制定条纹率滤波器，雕刻的有效的主波束的天线在干涉仪。正如我们所示，通过条纹率滤波的光束整形可以用于优化各种应用的测量，包括制图，最大限度地减少偏振泄漏，抑制仪器系统，并提高功率谱测量的灵敏度。我们表明，条纹率滤波自然出现在许多这些问题的最小方差处理，使最佳的基于可测量性的方法来分析干涉数据，避免系统学可能引入的传统方法，如成像。我们的技术最近在Ali等人（2015）中得到了证明，其中对再电离的21 cm功率谱设置了新的上限，展示了条纹率滤波成功提高灵敏度并减少系统学对深度观测的影响的能力。
英文摘要：
We generalize the technique of fringe-rate filtering, whereby visibilities measured by a radio interferometer are re-weighted according to their temporal variation. As the Earth rotates, radio sources traverse through an interferometer's fringe pattern at rates that depend on their position on the sky. Capitalizing on this geometric interpretation of fringe rates, we employ time-domain convolution kernels to enact fringe-rate filters that sculpt the effective primary beam of antennas in an interferometer. As we show, beam sculpting through fringe-rate filtering can be used to optimize measurements for a variety of applications, including mapmaking, minimizing polarization leakage, suppressing instrumental systematics, and enhancing the sensitivity of power-spectrum measurements. We show that fringe-rate filtering arises naturally in minimum variance treatments of many of these problems, enabling optimal visibility-based approaches to analyses of interferometric data that avoid systematics potentially introduced by traditional approaches such as imaging. Our techniques have recently been demonstrated in Ali et al. (2015), where new upper limits were placed on the 21 cm power spectrum from reionization, showcasing the ability of fringe-rate filtering to successfully boost sensitivity and reduce the impact of systematics in deep observations.
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