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SUMMARY:Sub-band Extensions to Measure Scattering with the Arrival-Times P
 ipeline for Repeating Fast Radio Bursts
DTSTART;VALUE=DATE-TIME:20261028T181700Z
DTEND;VALUE=DATE-TIME:20261028T181800Z
DTSTAMP;VALUE=DATE-TIME:20261025T203337Z
UID:indico-contribution-3704@nyx.physics.mcgill.ca
DESCRIPTION:Speakers: Victor Pop (McMaster University)\nFast radio bursts 
 (FRBs) are millisecond-duration extragalactic radio transients\, a subset 
 of which repeat. Multipath propagation through ionized media convolves eac
 h burst with a one-sided exponential\, producing a scattering tail whose t
 imescale scales steeply with frequency\, τ ∝ ν^α with α ≈ −4. An
  observed burst width\, however\, also carries contributions from intrinsi
 c emission\, instrumental sampling\, residual dispersion\, drift smearing\
 , and unresolved sub-bursts\, several of which produce asymmetric profiles
 .\nSub-band methods have been widely used to estimate FRB scattering. Here
  we present a sub-band extension to the per-channel arrival-times pipeline
  of Chamma et al. (2025)\, designed to estimate scattering only where the 
 data support it. Each profile is fit with an exponentially modified Gaussi
 an (EMG)\, with an FRBs spectral bandwidth further divided into dedrifted 
 sub-bands. The recovered tail timescales are fit with a power law\, where 
 only an index within the empirical range −4.4 ≤ α ≤ −3.6 licenses
  a scattering interpretation.\nAs a preliminary single-burst demonstration
 \, we apply the pipeline to FRB 20210415C from the second CHIME/FRB repeat
 er catalogue. Seven sub-bands across 420–760 MHz yield α = −3.94 ± 0
 .12\, consistent with thin-screen scattering. Initial tests on simulated b
 ursts suggest the index is robust. While these results are preliminary\, w
 e estimate that the scattering tail exceeds Galactic model predictions alo
 ng this sightline by ~400×\, pointing to non-Galactic scattering. This wo
 rk highlights the importance of further efforts to separate scattering fro
 m other broadening processes.\n\nhttps://nyx.physics.mcgill.ca/event/587/c
 ontributions/3704/
LOCATION:Online 
URL:https://nyx.physics.mcgill.ca/event/587/contributions/3704/
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