Robust sparse image reconstruction of radio interferometric observations with purify. Issue 1 (9th September 2017)

• Record Type: Journal Article
• Authors: Pratley, Luke; McEwen, Jason D.; d'Avezac, Mayeul; Carrillo, Rafael E.; Onose, Alexandru; Wiaux, Yves
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 473:Issue 1(2018)
• Page Start: 1038
• Page End: 1058
• Publication Date: 2017-09-09
• Subjects: techniques: image processing -- techniques: interferometric; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stx2237
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract: Next-generation radio interferometers, such as the Square Kilometre Array, will revolutionize our understanding of the Universe through their unprecedented sensitivity and resolution. However, to realize these goals significant challenges in image and data processing need to be overcome. The standard methods in radio interferometry for reconstructing images, such as clean, have served the community well over the last few decades and have survived largely because they are pragmatic. However, they produce reconstructed interferometric images that are limited in quality and scalability for big data. In this work, we apply and evaluate alternative interferometric reconstruction methods that make use of state-of-the-art sparse image reconstruction algorithms motivated by compressive sensing, which have been implemented in the purify software package. In particular, we implement and apply the proximal alternating direction method of multipliers algorithm presented in a recent article. First, we assess the impact of the interpolation kernel used to perform gridding and degridding on sparse image reconstruction. We find that the Kaiser-Bessel interpolation kernel performs as well as prolate spheroidal wave functions while providing a computational saving and an analytic form. Secondly, we apply purify to real interferometric observations from the Very Large Array and the Australia Telescope Compact Array and find that images recovered by purify are of higher quality than those recovered by clean . Thirdly, we discuss how purify reconstructions exhibit additional advantages over those recovered by clean . The latest version of purify, with developments presented in this work, is made publicly available.