Localizing FRBs through VLBI with the Algonquin Radio Observatory 10-m Telescope

TL;DR

This paper demonstrates a VLBI system using the Algonquin 10-m telescope to localize FRBs with approximately 50 mas precision, validating the approach with Crab pulsar signals and a simultaneous FRB detection, advancing FRB localization techniques.

Contribution

The paper introduces a new VLBI testbed with a refurbished 10-m dish for FRB localization, achieving ~50 mas precision and validating the system with Crab pulsar and FRB observations.

Findings

Localization precision of 50 mas achieved.

First cross-correlation of an FRB between CHIME and the 10-m telescope.

System validated with Crab pulsar signals.

Abstract

The 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 ~<30 masec precision. 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 phase-referencing an FRB event. We find a localization of 50 masec is possible with the performance of the current system. 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 1e-8 pc/cc 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 FRB cross-correlated in this very long baseline. This project serves as a testbed for the forthcoming CHIME/FRB Outriggers project.