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

TL;DR

This study applies bias correction to CHIME FRB data, revealing a population spectrum that suggests FRBs are more common at low frequencies and indicating potential differences in origins between repeaters and non-repeaters.

Contribution

It introduces an advanced bias correction method incorporating property correlations to analyze FRB populations and spectra using CHIME data.

Findings

FRB population spectrum follows a power-law with index -2.29.

Active repeaters and non-repeaters may have different progenitors.

More low-DM, short/long-width, and short-scattering events likely exist.

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 upon the bias correction method using pulse injections for the first CHIME/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 $F(\nu)\propto\nu^{\alpha}$, where $\alpha=-2.29\pm0.29$. This confirms previous indications that FRBs are brighter or more numerous at low frequencies. Analysing non-repeaters only, we find $\alpha=-2.50\pm0.43$, while including all bursts from repeaters produces $\alpha=-1.91\pm0.20$. This hints that active repeaters, low-rate repeaters, and non-repeaters may have different progenitors, mechanisms, or evolutionary stage.