An Image-based Blind Search for Fast Radio Bursts in 88 hr of Data from the EoR0 Field, with the Murchison Widefield Array

Abstract

This work is part of ongoing efforts to detect fast radio bursts using the Murchison Widefield Array (MWA) in a spectral window below 300 MHz. We used an image-based method based on the pilot study of Tingay et al., scaled up via massively parallel processing using a commercial supercomputer. We searched 87.6 hr of 2 s snapshot images, each covering 1165 square degrees of the EoR0 field, over a dispersion measure range of 170–1035 pc cm−3. The large amount of data necessitated the construction of a series of filters to classify and reject the large number of false positives. Our search was more sensitive than any previous blind search using the MWA telescope, but we report no fast radio bursts detections, a result which is consistent with the extrapolation into the low-frequency domain of the results of M. Sokolowski et al. We obtain upper bounds on the event rate ranging from <1783 sky−1 day−1 at a fluence of 392 Jy ms, to <31 sky−1 day−1 at 8400 Jy ms, for our spectral window of 167–198 MHz. Our method was shown to be computationally efficient and scalable by the two or three orders of magnitude required to seriously test the model of Sokolowski et al. Our process is especially sensitive to detections of satellites and meteor trails and may find applications in the identification of these transients. We comment on future surveys using this method, with both the MWA and the SKA.