Morphology of 35 Repeating Fast Radio Burst Sources at Microsecond Time Scales with CHIME/FRB

The Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) project has discovered the most repeating FRB sources of any telescope. However, most of the physical conclusions derived from this sample are based on data with a time resolution of ∼1 ms. In this work, we present for the first time a morphological analysis of the raw voltage data for 124 bursts from 35 of CHIME/FRB's repeating sources. We do not find any significant correlations among fluence, dispersion measure (DM), burst rate, and burst duration. Performing the first large-scale morphological comparison at timescales down to microseconds between our repeating sources and 125 nonrepeating FRBs, we find that repeaters are narrower in frequency and broader in duration than nonrepeaters, supporting previous findings. However, we find that the duration-normalized sub-burst widths of the two populations are consistent, possibly suggesting a shared physical emission mechanism. Additionally, we find that the spectral fluences of the two are consistent. When combined with the larger bandwidths and previously found larger DMs of nonrepeaters, this suggests that nonrepeaters may have higher intrinsic specific energies than repeating FRBs. We do not find any consistent increase or decrease in the DM (⪅1 pc cm⁻³ yr⁻¹) and scattering timescales (⪅2 ms yr⁻¹) of our sources over ∼2–4 yr periods.