Debiasing the Observed Fast Radio Burst Population with the CHIME/FRB Selection Function
Kyle McGregor, Jason W. T. Hessels, Victoria M. Kaspi, Kaitlyn Shin, Fengqiu A. Dong, Naman Jain, Robert A. Main, Mawson W. Sammons, Michele Woodland, Daniel Amouyal, Derek Bingham, Charanjot Brar, Amanda M. Cook, Radu Craiu, Alice P. Curtin, Gwendolyn Eadie, Bryan M. Gaensler, Jeff Huang, Afrokk Khan, Calvin Leung, Kiyoshi W. Masui, Ayush Pandhi, Swarali Shivraj Patil, Aaron B. Pearlman, Sachin Pradeep E. T., Paul Scholz, Seth R. Siegel, Kendrick Smith, David C. Stenning
astro-ph.HE
Submitted: 2026-06-24
Comments: 25 pages, 10 figures, submitted to ApJ
Code: https://github.com/CHIMEFRB/chimefrb-selection
License: http://creativecommons.org/licenses/by/4.0/
The gist: The recent release of CHIME/FRB Catalog 2 provides the largest sample to date with which to investigate the intrinsic distributions of fast radio bursts (FRBs).
Terminology
Abstract
The recent release of CHIME/FRB Catalog 2 provides the largest sample to date with which to investigate the intrinsic distributions of fast radio bursts (FRBs). Leveraging an expanded campaign of 587,367 synethetic bursts injected into the live CHIME/FRB search pipeline, we perform a population analysis of the fluence, scattering timescale, pulse width, and dispersion measure distributions of Catalog 2 FRBs. We first infer the intrinsic population using a resampling-based framework that accounts for instrumental selection effects following previous CHIME/FRB population studies. A central goal of this work is to constrain the intrinsic distribution of scattering timescales, that remained weakly constrained in Catalog 1 owing to limited statistics at moderate and large scattering times (tau 10, ms at 600 MHz) and sparse injection coverage in this regime. Second, we construct an explicit multidimensional selection function by training a logistic regression model on the injected events. This model estimates the detection probability as a function of FRB observable properties, including higher-order interaction terms. We incorporate this selection function into a simulation-based inference framework to refine the inferred intrinsic scattering-timescale distribution. We find evidence for a slight downturn in the intrinsic FRB scattering timescale distribution, though a flat or slightly rising distribution cannot be ruled out, that is further supported through a comparison with the higher-frequency scattering timescale distribution observed by Commensal Real-time ASKAP Fast Transients (CRAFT) survey.
Sources
- Discovery of 30 Repeating Fast Radio Burst Sources and Uniform Population Statistics of 80 Repeating Sources from CHIME/FRB
- CHIME/Slow overview and pilot survey: A new backend to search for second-duration radio transients with the CHIME telescope
- A 4200-hour HyperFlash and 'ECLAT campaign on the hyperactive FRB 20240114A: constraining energetics with the most brilliant bursts
- PyTorch: An Imperative Style, High-Performance Deep Learning Library
- Probing the maximum energy of fast radio bursts using thousands of sources from the Second CHIME/FRB Catalog
- Measurement of the Dispersion$\unicode{x2013}$Galaxy Cross-Power Spectrum with the Second CHIME/FRB Catalog
- Improved Horvitz-Thompson Estimator in Survey Sampling
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