Kavli Affiliate: Kiyoshi W. Masui
| First 5 Authors: Ketan R. Sand, Alice P. Curtin, Daniele Michilli, Victoria M. Kaspi, Emmanuel Fonseca
| Summary:
We present a spectro-temporal analysis of 137 fast radio bursts (FRBs) from
the first CHIME/FRB baseband catalog, including 125 one-off bursts and 12
repeat bursts, down to microsecond resolution using the least-squares
optimization fitting routine: fitburst. Our measured values are compared with
those in the first CHIME/FRB intensity catalog, revealing that nearly one-third
of our sample exhibits additional burst components at higher time resolutions.
We measure sub-burst components within burst envelopes as narrow as $sim$23
$mu$s (FWHM), with 20% of the sample displaying sub-structures narrower than
100 $mu$s, offering constraints on emission mechanisms. Scattering timescales
in the sample range from 30 $mu$s to 13 ms at 600 MHz. We observe no
correlations between scattering time and dispersion measure, rotation measure,
or linear polarization fraction, with the latter suggesting that depolarization
due to multipath propagation is negligible in our sample. Bursts with narrower
envelopes ($leq$ 1 ms) in our sample exhibit higher flux densities, indicating
the potential presence of sub-ms FRBs that are being missed by our real-time
system below a brightness threshold. Most multicomponent bursts in our sample
exhibit sub-burst separations of $leq$ 1 ms, with no bursts showing
separations $<$41 $mu$s, even at a time resolution of 2.56 $mu$s, but both
scattering and low signal-to-noise ratio can hinder detection of additional
components. Lastly, given the morphological diversity of our sample, we suggest
that one-off and repeating FRBs can come from different classes but have
overlapping property distributions.
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