2021PASP..133b4101Y

We perform the quasi-periodic oscillation (QPO) analysis of blazar PKS 1424-418 in the γ-ray (0.1-300 GeV) band from 2009 May 12 to 2019 September 17 (MJD 54963-58743). Using the spectral domain methods, Bhatta & Dhital reported that this source has 353 days periodic flux oscillations in the γ-ray flux. Adopting time domain methods, we confirm the previous detection that a possible γ-ray QPO of ∼355 days with the high significance level. Combining two methods of time domain and spectral domain provides stronger evidence for the existence of the QPO. Especially, after the strongest flare, γ-ray light-curve exhibits stronger periodic significance compared with the whole observation period. Assuming that the QPO is come from the orbital motion in a supermassive binary black hole system, the mass of primary black hole for this source is estimate as M ∼ 3.5 x 10⁸-5.5 x 10⁹ M_☉.