Polarization Pipeline for Fast Radio Bursts Detected by CHIME/FRB
Name
Mckinven_2021_ApJ_920_138.pdf
Description
Published version
Size
3.39 MB
Format
Adobe PDF
Checksum (MD5)
b09521bd3836ff2ab5ea22015ac467f4
Author(s)
Mckinven, R
Michilli, D
Masui, K
Cubranic, D
Gaensler, BM
Ng, C
Bhardwaj, M
Leung, C
Boyle, PJ
Brar, C
Date Issued
2021
Journal
Astrophysical Journal
Publisher
American Astronomical Society
Citation
Mckinven, R, Michilli, D, Masui, K, Cubranic, D, Gaensler, BM et al. 2021. "Polarization Pipeline for Fast Radio Bursts Detected by CHIME/FRB." Astrophysical Journal, 920 (2).
Version
Final published version
Abstract
Polarimetric observations of Fast Radio Bursts (FRBs) are a powerful resource
for better understanding these mysterious sources by directly probing the
emission mechanism of the source and the magneto-ionic properties of its
environment. We present a pipeline for analysing the polarized signal of FRBs
captured by the triggered baseband recording system operating on the FRB survey
of The Canadian Hydrogen Intensity Mapping Experiment (CHIME/FRB). Using a
combination of simulated and real FRB events, we summarize the main features of
the pipeline and highlight the dominant systematics affecting the polarized
signal. We compare parametric (QU-fitting) and non-parametric (rotation measure
synthesis) methods for determining the Faraday rotation measure (RM) and find
the latter method susceptible to systematic errors from known instrumental
effects of CHIME/FRB observations. These errors include a leakage artefact that
appears as polarized signal near $\rm{RM\sim 0 \; rad \, m^{-2}}$ and an RM
sign ambiguity introduced by path length differences in the system's
electronics. We apply the pipeline to a bright burst previously reported by
\citet[FRB 20191219F;][]{Leung2021}, detecting an $\mathrm{RM}$ of $\rm{+6.074
\pm 0.006 \pm 0.050 \; rad \, m^{-2}}$ with a significant linear polarized
fraction ($\gtrsim0.87$) and strong evidence for a non-negligible circularly
polarized component. Finally, we introduce an RM search method that employs a
phase-coherent de-rotation algorithm to correct for intra-channel
depolarization in data that retain electric field phase information, and
successfully apply it to an unpublished FRB, FRB 20200917A, measuring an
$\mathrm{RM}$ of $\rm{-1294.47 \pm 0.10 \pm 0.05 \; rad \, m^{-2}}$ (the second
largest unambiguous RM detection from any FRB source observed to date).
MIT Department
MIT Kavli Institute for Astrophysics and Space Research
Massachusetts Institute of Technology. Department of Physics
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.3847/1538-4357/AC126A
