J/AJ/168/153 Image-based blind search for FRBs in MWA 8yrs obs. (Kemp+, 2024)
An image-based blind search for fast radio bursts in 88hr of data from the
EoR0 field, with the Murchison Widefield Array.
Kemp I., Tingay S., Midgley S., Mitchell D.
<Astron. J., 168, 153 (2024)>
=2024AJ....168..153K 2024AJ....168..153K
ADC_Keywords: Radio sources
Keywords: Radio transient sources ; Radio astronomy ; Computational methods
Abstract:
This work is part of ongoing efforts to detect fast radio bursts using
the Murchison Widefield Array (MWA) in a spectral window below 300MHz.
We used an image-based method based on the pilot study of
Tingay+ 2015AJ....150..199T 2015AJ....150..199T, scaled up via massively parallel
processing using a commercial supercomputer. We searched 87.6hr of 2s
snapshot images, each covering 1165 square degrees of the EoR0 field,
over a dispersion measure range of 170-1035pc/cm3. 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 Sokolowski+ 2024PASA...41...11S 2024PASA...41...11S. We obtain
upper bounds on the event rate ranging from <1783sky-1day-1 at a
fluence of 392Jy.ms, to <31sky-1day-1 at 8400Jy.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.
Description:
To date there have been four Fast radio burst (FRB) searches using the
Murchison Widefield Array (MWA). These have employed both high time
resolution, using the Voltage Capture System (VCS), and blind image
searches (see Table 1). These four searches returned no FRB
detections.
The data set considered in this paper is a collection of 3348 files,
each containing approximately 2 minutes of visibility data, totaling
107.1hr of observations of the Epoch of Reionization (EoR) 0 field
centered at RA=00,DEC=-27° (Pober+ 2016ApJ...819....8P 2016ApJ...819....8P).
2027 observations were of 112s duration and 1321 were of 120s
duration.
Observations were obtained on 127 distinct days between 2013 August 14
and 2021 December 8, and are listed in Table 2.
The 3348 observations included 1504 (45% of the total) collected with
the array in the Phase I configuration (Tingay+ 2013PASA...30....7T 2013PASA...30....7T)
and 1844 (55%) in the Phase II compact configuration
(Wayth+ 2018PASA...35...33W 2018PASA...35...33W). The maximum baselines for the two
configurations were 2438m and 750m, respectively. Phase I data were
processed to images of 1024x1024 pixels with 2' pixel size, Phase II
data were processed to 256x256 pixels with 8' pixel size.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 64 3348 Murchison Widefield Array (MWA) observations
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See also:
J/other/PASA/33.45 : FRBCAT: The Fast Radio Burst (FRB) Cat. (Petroff+, 2016)
J/ApJS/257/59 : First CHIME/FRB Fast Radio Burst Cat. (CHIME/FRB Col.+, 2021)
J/A+A/675/A99 : FRBs search with Fermi-LAT (Principe+, 2023)
http://github.com/MWATelescope : MWA's public code repository
http://asvo.mwatelescope.org/ : MWA All-Sky Virtual Observatory
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 I10 --- ObsID [1060539904/1322827024] Observation ID
12- 21 A10 "D/M/Y" StartDate UTC start date
23- 30 A8 "h:m:s" StartTime UTC start time
32- 39 A8 "h:m:s" StopTime UTC stop time
41 A1 --- Cat Observation category (1)
43- 64 A22 --- Det Satellites detected; column added by CDS
from Table 5 (2)
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Note (1): Observation category as in Table 3:
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Cat Description MWA Telescope Calibration Count Dur Img Size Img
Configuration (hr) (pix) Res
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A Tingay+ 2015 Phase I Extended Cotter 334 10.4 1024x1024 2"
B EoR extended Phase I Extended Hyperdrive 1170 36.4 1024x1024 2"
C EoR compact Phase II Compact Hyperdrive 1844 60.3 256x256 8"
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Note (2): Name and NORAD number or "u" for unidentified satellite.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Feb-2025