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Abstract:

Radio frequency interference (RFI), the presence of artificial and/or terrestrial signals in astronomical data, poses a great challenge to the search for pulsars and radio transients, such as rotating radio transients (RRATs) and fast radio bursts (FRBs), by obscuring or distorting the signal of interest and resulting in large numbers of erroneous detections. RFI mitigation algorithms aim to remove this interference and improve the chance of detection of transients, but with the growing number of techniques, selecting the most appropriate method for a given survey can be problematic. The choice of method is particularly important in real-time searches planned for next-generation telescopes such as those of the SKAO, where there is no possibility to reprocess the data. In this paper, we explore the algorithm selection problem by injecting pulses into data which simulates several RFI environments. A set of these files is then cleaned using RFI mitigation algorithms and run through a single pulse search pipeline to analyse the recovery of the injected pulses. We examine the recovery of the injected single pulses with an emphasis on a number of cases spanning a range of pulse brightness, width, and dispersion measure. The efficacy and side effects of a few popular RFI excision methods, namely IQRM, SKF, and ZDMF are evaluated.

Abstract:

Retraction to: Naturehttps://doi.org/10.1038/s41586-022-04841-8 Published online 13 July 2022 The authors have retracted this article after identifying a crucial error: due to an unusual calibration problem, CHIME’s digital beams were incorrectly pointed when FRB 20191221A was detected. The sub-second periodicity that they associated with the putative fast radio burst FRB 20191221A was, in reality, a periodic signal from the known Galactic pulsar PSR J0248 + 6021. This directly impacts the conclusions drawn about the periodicity of FRB 20191221A and its possible origins. The authors note that the paper also reports the tentative detections of periodicity in two other sources, FRBs 20210206A and 20210213A, which are unaffected by the aforementioned short-lived digital mispointing issue. No other FRB detections published by CHIME/FRB were affected by this very unusual problem. The technical details for it have now been published by the author as a preprint ¹. All authors agree to this retraction.