2026ApJ...996...40Z

The periodicity of repeating fast radio bursts (FRBs) is crucial for understanding their origins and usually requires appropriate methods to identify. In a recent paper, we developed the Phase-folding probability Binomial Analysis (PBA) periodogram and found a candidate period of 4.605 days for FRB 20121102A. As a follow-up, thorough tests of the PBA method are first performed using numerically generated data in this paper. The tests are done for observations of 20 hr with different observation windows. PBA shows its different effects in identifying the periodicity of bursts compared with the Lomb-Scargle periodogram and χ² test. The PBA method is particularly sensitive for bursty sources with high burst rates (R ≥ 2 hr^–1), narrow active phase widths (ΔP ≤ 0.2), and a high percentage of bursts that show periodicity (p_b ≥ 0.8). We then apply PBA to analyze the periodicity of bursts from FRB 20190520B, aiming toward periods ranging from 1 day to 1024 days. For bursts with fluences higher than 0.5 Jy ms, a period of $381.1{4}_{-0.29}^{+1.25}$ days with an active phase width of 0.1 is identified. For bursts with fluences lower than 0.5 Jy ms, no periodicity is detected.