Bias-corrected Fast Radio Burst Population and Spectra Using CHIME Injection Data

Abstract Fast radio bursts (FRBs), a class of millisecond-scale, highly energetic phenomena with unknown progenitors and radiation mechanisms, require proper statistical analysis as a key method for uncovering their mysteries. In this research, we build on the bias correction method using pulse injections for the first Canadian Hydrogen Intensity Mapping Experiment/FRB catalog, to include correlations between properties and to analyze the FRB population spectrum. This model includes six FRB properties: dispersion measure (DM), pulse width, scattering timescale, spectral index, spectral running, and fluence. By applying the multidimensional weight function calculated by the model, we update the corrected distributions, suggesting that more low-DM, short- and long-width, and short-scattering timescale events may exist. Using one-off events and the first bursts from repeaters, the derived intrinsic population spectrum has a best-fit power law of F ( ν ) ∝ ν α , where α = −2.29 ± 0.29. This confirms previous indications that FRBs are brighter or more numerous at low frequencies. Analyzing nonrepeaters only, we find α = −2.50 ± 0.43, while including all bursts from repeaters produces α = −1.91 ± 0.20. This hints that active repeaters, low-rate repeaters, and nonrepeaters may have different progenitors, mechanisms, or evolutionary stages.