Distribution of Fast Radio Burst Dispersion Measures in CHIME/FRB Catalog 1: Implications on the Origin of FRBs

Abstract

Recently, CHIME/FRB project published its first fast radio burst (FRB) catalog (hereafter, Catalog 1), which contains in total 536 unique bursts. With the help of the latest set of FRBs in this large-size catalog, we aim to investigate the dispersion measure (DM) or redshift ( $$z$$ ) distribution of the FRB population, and solution of this problem could be used to clarify the question of FRB origin. In this study, we adopted the M&E 2018 model to fit the observed $$z$$ distribution of FRBs in Catalog 1. In the M&E 2018 model, we are mostly interested in the $$\Phi (z)$$ function, i.e., number of bursts per proper time per comoving volume, which is represented by the star formation rate (SFR) with a power-law index $$n$$ . Our estimated value of $$n$$ is $$0.0_{{ - 0.0}}^{{ + 0.6}}$$ ( $$0.0_{{ - 0.0}}^{{ + 2.1}}$$ ) at the 68 (95) per cent confidence level, implying that the FRB population evolves with redshift consistent with, or faster than, the SFR. Specially, the consistency of the $$n$$ values estimated by this study and the SFR provides a potential support for the hypothesis of FRBs originating from young magnetars.