A generic and efficient E-field Parallel Imaging Correlator for next-generation radio telescopes
A generic and efficient E-field Parallel Imaging Correlator for next-generation radio telescopes
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DOI：
10.1093/mnras/stx113
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发表时间：
2015-10
影响因子：
4.8
通讯作者：
N. Thyagarajan;A. Beardsley;J. Bowman;M. Morales
中科院分区：
文献类型：
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作者：
N. Thyagarajan;A. Beardsley;J. Bowman;M. Morales
现代射电望远镜倾向于具有大量天线的密集阵列布局（$N_\textrm{a}\gtrsim 1000$）。由于传统相关器的复杂性为 $\mathcal{O}(N_\textrm{a}^2)$，因此要实现这些强大仪器的全部成像潜力将需要高昂的成本。通过我们通用且高效的电场并行成像相关器 (EPIC)，我们首次展示了通用直接成像算法的软件演示，即模块化最佳频率傅里叶 (MOFF) 成像仪。它利用了傅立叶变换的乘法卷积定理。它不仅将密集布局的成本降低到 $\mathcal{O}(N_\textrm{a}\log_2 N_\textrm{a})$，而且还可以从不规则排列的异构天线进行成像。 EPIC 是高度模块化和可并行化的，以面向对象的 Python 实现，并且公开可用。我们已经验证生成的图像与使用传统技术生成的图像等效，且精度在由网格粗糙度确定的范围内。我们还验证了我们对长波长阵列 (LWA) 观察到的数据的实施。由大量天线组成的密集填充因子的天线布局，如 LWA、平方公里阵列、再电离阵列的氢时代和加拿大氢强度测绘实验，将通过部署 EPIC 获得显着的计算优势。数字化仪写入时间尺度上校准时域图像的固有可用性以及相对于基于可见度的系统大大降低的 I/O 带宽将使其成为快速射电爆发 (FRB) 以及行星和系外行星现象瞬态搜索的主要候选者。
Modern radio telescopes are favouring densely packed array layouts with large numbers of antennas ($N_\textrm{a}\gtrsim 1000$). Since the complexity of traditional correlators scales as $\mathcal{O}(N_\textrm{a}^2)$, there will be a steep cost for realizing the full imaging potential of these powerful instruments. Through our generic and efficient E-field Parallel Imaging Correlator (EPIC), we present the first software demonstration of a generalized direct imaging algorithm, namely, the Modular Optimal Frequency Fourier (MOFF) imager. It takes advantage of the multiplication-convolution theorem of Fourier transforms. Not only does it bring down the cost for dense layouts to $\mathcal{O}(N_\textrm{a}\log_2 N_\textrm{a})$ but can also image from irregularly arranged heterogeneous antenna. EPIC is highly modular and parallelizable, implemented in object oriented Python, and publicly available. We have verified the images produced to be equivalent to those produced using traditional techniques to within a precision determined by coarseness of gridding. We have also validated our implementation on data observed with the Long Wavelength Array (LWA). Antenna layouts with a dense filling factor consisting of a large number of antennas such as LWA, the Square Kilometre Array, Hydrogen Epoch of Reionization Array, and Canadian Hydrogen Intensity Mapping Experiment will gain significant computational advantage by deploying EPIC. Inherent availability of calibrated time-domain images on digitizer writeout time-scales and vastly lower I/O bandwidth relative to visibility-based systems will make it a prime candidate for transient searches of Fast Radio Bursts (FRB) as well as planetary and exoplanetary phenomena.