An analysis pipeline for CHIME/FRB full-array baseband data

TL;DR

This paper presents an analysis pipeline for processing full-array baseband data from CHIME/FRB, enabling precise localization, polarization studies, and temporal substructure analysis of fast radio bursts.

Contribution

It introduces an automated pipeline for offline analysis of CHIME/FRB baseband data, achieving sub-arcminute localization and detailed polarization and temporal studies.

Findings

Sub-arcminute localization accuracy achieved

Detection of polarization and Faraday rotation

Resolution of microsecond temporal substructure

Abstract

The Canadian Hydrogen Intensity Mapping Experiment (CHIME) has become a leading facility for detecting fast radio bursts (FRBs) through the CHIME/FRB backend. CHIME/FRB searches for fast transients in polarization-summed intensity data streams that have 24-kHz spectral and 1-ms temporal resolution. The intensity beams are pointed to pre-determined locations in the sky. A triggered baseband system records the coherent electric field measured by each antenna in the CHIME array at the time of FRB detections. Here we describe the analysis techniques and automated pipeline developed to process these full-array baseband data recordings. Whereas the real-time FRB detection pipeline has a localization limit of several arcminutes, offline analysis of baseband data yields source localizations with sub-arcminute precision, as characterized by using a sample of pulsars and one repeating FRB with known positions. The baseband pipeline also enables resolving temporal substructure on a micro-second scale and the study of polarization including detections of Faraday rotation.