A Generic and Efficient E-field Parallel Imaging Correlator for Next-Generation Radio Telescopes

Abstract

Modern radio telescopes are favouring densely packed array layouts with large numbers of antennas ($N_{\text{A}}\gtrsim 1000$). Since the complexity of traditional correlators scales as $\mathcal{O}(N_{\text{A}}^2)$, 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. Not only does it bring down the cost for dense layouts to $\mathcal{O}(N_{\text{A}}{\log }_2{N}_{\text{A}})$ but can also image from irregular layouts and heterogeneous arrays of antennas. EPIC is highly modular, parallelizable, implemented in object-oriented Python, and publicly available. We have verified the images produced to be equivalent to those from traditional techniques to within a precision set by gridding coarseness. We have also validated our implementation on data observed with the Long Wavelength Array (LWA1). We provide a detailed framework for imaging with heterogeneous arrays and show that EPIC robustly estimates the input sky model for such arrays. Antenna layouts with dense filling factors 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 an optimized version of EPIC. The algorithm is a strong candidate for instruments targeting transient searches of Fast Radio Bursts (FRB) as well as planetary and exoplanetary phenomena due to the availability of high-speed calibrated time-domain images and low output bandwidth relative to visibility-based systems.

Accepted in MNRAS, 17 pages, 14 figures

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• Canadian Hydrogen Intensity Mapping Experiment (CHIME) Pathfinder
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Cited by in corpus (10)

• Data Analysis for Precision 21 cm Cosmology
• Redundant-Baseline Calibration of the Hydrogen Epoch of Reionization Array
• Dispersion by pulsars, magnetars, fast radio bursts and massive electromagnetism at very low radio frequencies
• A Real-Time, All-Sky, High Time Resolution, Direct Imager for the Long Wavelength Array
• An Efficient Feedback Calibration Algorithm for Direct Imaging Radio Telescopes
• Optimization and Commissioning of the EPIC Commensal Radio Transient Imager for the Long Wavelength Array
• Real-time stream processing in radio astronomy
• Calibration Schemes with $\mathcal{O}(N\log N)$ Scaling for Large-N Radio Interferometers Built on a Regular Grid
• BIPP: An efficient HPC implementation of the Bluebild algorithm for radio astronomy
• Direct Wide-Field Radio Imaging in Real-Time at High Time Resolution using Antenna Electric Fields