A statistical analysis of fluence and energy distributions of non-repeating fast radio bursts detected by CHIME

ABSTRACT Fast radio bursts (FRBs) are energetic radio bursts that typically last for milliseconds. They are mostly of extragalactic origin, but the progenitors, trigger mechanisms, and radiation processes are still largely unknown. Here, we present a comprehensive analysis on 415 non-repeating FRBs detected by CHIME (Canadian Hydrogen Intensity Mapping Experiment), applying manual filtering to ensure sample completeness. It is found that the distribution of fluence can be approximated by a three-segment power-law function, with the power-law indices being $-3.76 \pm 1.61$, $0.20 \pm 0.68$, and $2.06 \pm 0.90$ in the low, middle, and high-fluence segments, respectively. Both the total dispersion measure (DM) and the extragalactic DM follow a smoothly broken power-law distribution, with characteristic break DM values of $\sim 703$ and $\sim 639$ pc $\mathrm {cm}^{-3}$, respectively. The redshifts are estimated from the extragalactic DM by using the Macquart relation, which are found to peak at $z \sim 0.6$. The isotropic energy release ($E_{\text{iso}}$) is also derived for each burst. Two-Gaussian components are revealed in the distribution of $E_{\text{iso}}$, with the major population narrowly clustered at $\sim 2.3 \times 10^{40}\, {\rm erg}$. The minor population have a characteristic energy of $\sim 1.6 \times 10^{39}$ erg and span approximately one order of magnitude. The distribution hints a near-uniform energy release mechanism for the dominant population as expected from some catastrophic channels, whereas the lower energy component (potentially including repeat-capable sources) may reflect a broader diversity in FRB origins, emission mechanisms, and evolutionary stages.