Possible quasi-periodic optical oscillations of ZTF blazars

Abstract

Based on the Zwicky Transient Facility (ZTF), we selected 10 blazars as our sample sources. Among these, we found four blazars (J 0923.5+4125, J 1221.3+3010, J 1503.5+4759, and J 1652.7+4024) showing possible indications of quasi periodic oscillations (QPOs) modulation. We conducted a detailed analysis of their optical light curves (g- and r-bands) over the past five years using the root mean square (RMS)-Flux relation, flux distribution, and QPO detection methods to investigate their variability characteristics. A linear RMS-Flux relation is present in both bands, and their flux distributions follow a log-normal form. This suggests that optical variability may arise from multiplicative, nonlinear processes across different timescales and flux states. Further QPO analysis using the weighted wavelet Z-transform (WWZ), Lomb-Scargle periodogram (LSP), and autoregressive integrated moving average (ARIMA) methods identified candidate periodic signals in four blazars. J 0923.5+4125 (period $\sim$ 205 days) and J 1221.3+3010 ($\sim$ 630 days) show local significances of $\sim 3\ddot{I}ƒ$, whereas J 1503.5+4759 ($\sim$ 38.5 days) and J 1652.7+4024 ($\sim$ 48 days) reach $\sim 4\ddot{I}ƒ$. After accounting for the look-elsewhere effect, the global significances for J 1503.5+4759 in the g- and r-bands are $\sim 2.7\ddot{I}ƒ$, while for J 1652.7+4024 they are approximately $\sim 2.5\ddot{I}ƒ$ in both bands. These two blazars warrant further monitoring and investigation.

25 pages, 4 tables, 7 figures, accepted for publication in JHEAp