Determine the bias from completeness cuts in FRB population analyses

Determine the actual bias in true fast radio burst population parameters caused by restricting analyses to completeness regions defined by confident host-galaxy identifications.

Background

Previous analyses using the z–DM framework restricted the data to FRBs with confident host associations, often imposing a maximum extragalactic dispersion measure so that the retained sample was presumed complete. Such cuts can preferentially exclude distant or high-redshift FRBs whose host galaxies are harder to identify, potentially biasing inferred population and cosmological parameters.

Synthetic tests in the paper suggest that the bias may be small for current samples, but the authors distinguish this simulated assessment from the unknown bias affecting the actual FRB population parameters inferred from real observations. The unresolved problem is therefore to quantify that bias rather than merely assess it in simulations.

References

While we have shown in \S\,\ref{sec:bias_estimate} that such biases with current FRB samples are likely to be small, confirming the conclusions of \citet{2026ApJ...999..202S}, the actual bias in true FRB population parameters (as opposed to our simulated estimates of the truth) remains unknown.

— Through a glass, darkly: a combined framework for estimating fast radio burst host galaxy and population properties in an era of uncertain host identification  (2609.04765 - James et al., 4 Sep 2026) in Section 7.1, “Overcoming completeness cuts in z–DM”