Flux Calibration of CHIME/FRB Intensity Data

TL;DR

This paper discusses the challenges of flux calibration for CHIME/FRB radio telescope data and introduces an automated pipeline to calibrate burst fluxes, providing lower-limit estimates with associated uncertainties.

Contribution

It presents a comprehensive review of flux calibration challenges and introduces an automated calibration pipeline for CHIME/FRB data, improving measurement reliability.

Findings

Calibration pipeline successfully processed 536 FRB events.

Flux measurements are lower limits due to localization limitations.

Uncertainties in flux estimates are quantified.

Abstract

Fast radio bursts (FRBs) are bright radio transients of micro-to-millisecond duration and unknown extragalactic origin. Central to the mystery of FRBs are their extremely high characteristic energies, which surpass the typical energies of other radio transients of similar duration, like Galactic pulsar and magnetar bursts, by orders of magnitude. Calibration of FRB-detecting telescopes for burst flux and fluence determination is crucial for FRB science, as these measurements enable studies of the FRB energy and brightness distribution in comparison to progenitor theories. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a radio interferometer of cylindrical design. This design leads to a high FRB detection rate but also leads to challenges for CHIME/FRB flux calibration. This paper presents a comprehensive review of these challenges, as well as the automated flux calibration software pipeline that was developed to calibrate bursts detected in the first CHIME/FRB catalog, consisting of 536 events detected between July 25th, 2018 and July 1st, 2019. We emphasize that, due to limitations in the localization of CHIME/FRB bursts, flux and fluence measurements produced by this pipeline are best interpreted as lower limits, with uncertainties on the limiting value.