Researchers Refine Method for Identifying Fast Radio Burst Host Galaxies Using Updated Bayesian Framework
Astronomers have extended the PATH Bayesian framework used to identify fast radio burst (FRB) host galaxies by incorporating physically-motivated priors based on expected host galaxy magnitudes. The updated method was calibrated using 32 FRBs detected by the Australian SKA Pathfinder (ASKAP) and increases confidence in host galaxy assignments. The work also confirms that FRB host galaxies are fainter than a star-formation-weighted distribution predicts, constraining theories about FRB progenitors.
A new study accepted by the Publications of the Astronomical Society of Australia (PASA) updates the Probabilistic Association of Transients to their Hosts (PATH) framework, the standard Bayesian tool for matching fast radio bursts to their host galaxies in optical images. The authors develop three models for the apparent r-band magnitude distribution of FRB host galaxies conditioned on expected redshift, combining them with redshift estimates derived from each FRB's dispersion measure. These new physically-motivated priors were fitted using host galaxy candidates for 32 FRBs from the CRAFT survey conducted with ASKAP in incoherent sum mode. Applying the updated framework increases confidence in the most probable host assignments across all tested events. The study statistically confirms that the true FRB host galaxy population is fainter than a star-formation-weighted distribution would predict (p-value 0.12%), while a mass-weighted distribution fits even more poorly (p-value 10⁻⁹). The three models produce similar predictions at low redshift (z ~ 0.1) but diverge at higher redshifts, meaning a larger sample of FRBs at z > 0.5 will be needed to distinguish between them. The authors note that future extensions incorporating host metallicity and other properties could further refine the framework.
What's missing
The study acknowledges that the three magnitude-prior models cannot yet be distinguished at high redshift (z > 0.5) due to limited sample size in that range. The analysis is also limited to ASKAP ICS-mode detections, and it is unclear how well the fitted priors generalize to FRBs detected by other instruments or localization methods.
What different sources said
- arXiv astro-phCenter
Updating the PATH framework with FRB host galaxy models
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