Abstract
Abstract The Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB experiment has detected thousands of fast radio bursts (FRBs) due to its sensitivity and wide field of view; however, its low angular resolution prevents it from localizing events to their host galaxies. Very long baseline interferometry (VLBI), triggered by FRB detections from CHIME/FRB will solve the challenge of localization for non-repeating events. Using a refurbished 10 m radio dish at the Algonquin Radio Observatory located in Ontario Canada, we developed a testbed for a VLBI experiment with a theoretical λ/D ≲ 30 mas. We provide an overview of the 10 m system and describe its refurbishment, the data acquisition, and a procedure for fringe fitting that simultaneously estimates the geometric delay used for localization and the dispersive delay from the ionosphere. Using single pulses from the Crab pulsar, we validate the system and localization procedure, and analyze the clock stability between sites, which is critical for coherently delay referencing an FRB event. We find a localization of ∼200 mas is possible with the performance of the current system (single-baseline). Furthermore, for sources with insufficient signal or restricted wideband to simultaneously measure both geometric and ionospheric delays, we show that the differential ionospheric contribution between the two sites must be measured to a precision of 1 × 10−8 pc cm−3 to provide a reasonable localization from a detection in the 400–800 MHz band. Finally we show detection of an FRB observed simultaneously in the CHIME and the Algonquin 10 m telescope, the first non-repeating FRB in this long baseline. This project serves as a testbed for the forthcoming CHIME/FRB Outriggers project.
Highlights
Fast radio bursts (FRBs) are bright, millisecond-long flashes of radio emission that were first discovered by Lorimer et al (2007) and have been observed to be distributed throughout the sky (Josephy et al 2021)
FRBs have been recorded in simultaneous dumps at Canadian Hydrogen Intensity Mapping Experiment (CHIME) and Algonquin Radio Observatory (ARO) 10 m telescope, but their signal-to-noise ratio (S/N)
In the presented work we have developed a testbed for the CHIME/FRB Outriggers project with the capability of studying FRB localizations, using pulsars to coherently delay reference, and demonstrated clock stability between an independent maser (ARO 10 m telescope) and global positioning system (GPS) crystal oscillator (CHIME)
Summary
Fast radio bursts (FRBs) are bright, millisecond-long flashes of radio emission that were first discovered by Lorimer et al (2007) and have been observed to be distributed throughout the sky (Josephy et al 2021) Their origins are among the key unresolved questions in astrophysics, despite hundreds of FRBs having been observed to date (Petroff et al 2016; The CHIME/ FRB Collaboration et al 2021). Despite the fact that some facilities are able to localize FRBs in limited numbers, localization remains a challenging problem (with the exception of low-redshift nearby events; Bhardwaj et al 2021) This is mainly due to the fact that most FRBs are non-repeating, and a large field of view (FOV) is required in order to increase the probability of detection. By achieving more precise localizations of non-repeating FRBs, we can constrain FRB populations (Marcote et al 2017; Kirsten et al 2021) and improve the classification for repeaters and non-repeaters, and put them to use as probes for fundamental astrophysics (Petroff et al 2019)
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