Cosmological Evolution of Fast Radio Bursts and Its Rapid Decline Relative to Star Formation Rate

Fast radio bursts (FRBs) are enigmatic millisecond-duration radio transients whose physical origins remain debated. To shed light on this, we analyze the CHIME/FRB Catalog 2. By using the probability distribution of the dispersion measure derived from the IllustrisTNG simulation, we compute the pseudo-redshift with 1 σ error for each FRB. To derive the FRB luminosity function and event rate, we employ a nonparametric statistical method. Building upon Efron–Petrosian method, we find strong luminosity evolution with redshift, well described by L 0 ∝ (1 + z ) 6.38 . After de-evolving this trend, we apply the Lynden-Bell c − method to derive the comoving FRB formation rate which is found to decline rapidly at high redshift, following ρ ( z ) ∝ (1 + z ) −5.38±0.02 . We also test the robustness of our results by considering the upper and lower limits of pseudo-redshifts and different flux limits of CHIME. Similar results are found. This steep decline is inconsistent with a direct tracing of the cosmic star formation rate but closely resembles the redshift evolution of short gamma-ray bursts—systems linked to compact object mergers. Our results support that the origin of FRBs is associated with old populations, such as neutron stars and black holes.