A VLBI Software Correlator for Fast Radio Transients

A VLBI Software Correlator for Fast Radio Transients

One major goal in fast radio burst science is to detect fast radio bursts (FRBs) over a wide field of view without sacrificing the angular resolution required to pinpoint them to their host galaxies. Wide-field detection and localization capabilities have already been demonstrated using connected-el...

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Bibliographic Details
Main Authors: Calvin Leung, Shion Andrew, Kiyoshi W. Masui, Charanjot Brar, Tomas Cassanelli, Shami Chatterjee, Victoria Kaspi, Kholoud Khairy, Adam E. Lanman, Mattias Lazda, Juan Mena-Parra, Gavin Noble, Aaron B. Pearlman, Mubdi Rahman, Pranav Sanghavi, Vishwangi Shah, (CHIME/FRB Collaboration)
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astronomical Journal
Subjects:
Radio transient sources
Radio pulsars
Open source software
Very long baseline interferometry
Radio astrometry
Interferometric correlation
Online Access:https://doi.org/10.3847/1538-3881/add876
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Summary:One major goal in fast radio burst science is to detect fast radio bursts (FRBs) over a wide field of view without sacrificing the angular resolution required to pinpoint them to their host galaxies. Wide-field detection and localization capabilities have already been demonstrated using connected-element interferometry; the CHIME/FRB Outriggers project will push this further using widefield cylindrical telescopes as widefield outriggers for very long baseline interferometry (VLBI). This paper describes an offline VLBI software correlator written in Python for the CHIME/FRB Outriggers project. It includes features well-suited to modern widefield instruments like multibeaming/multiple phase center correlation, pulse gating including coherent dedispersion, and a novel correlation algorithm based on the quadratic estimator formalism. This algorithm mitigates sensitivity loss that arises in instruments where the windowing and channelization is done outside the VLBI correlator at each station, which accounts for a 30% sensitivity drop away from the phase center. Our correlation algorithm recovers this sensitivity on both simulated and real data. As an end-to-end check of our software, we have written a preliminary pipeline for VLBI calibration and single-pulse localization, which we use in Lanman et al. to verify the astrometric accuracy of the CHIME/FRB Outriggers array.
ISSN:1538-3881

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