Detection of Quasiperiodic Oscillation on the Order of Days in Blazar PKS 0422+004 with TESS

We find that the optical band light curve of the blazar PKS 0422+004 observed by the Transiting Exoplanet Survey Satellite (TESS) has a quasiperiodic oscillation (QPO) of about 7.4 days in sector 32. We use the Lomb-Scargle Periodogram (LSP) method to search for significant periods, and further validate them using the Weighted Wavelet Z-transform (WWZ) method for time-frequency domain analysis. Finally, based on Schwarzschild black hole (a=0) and extreme Kerr black hole (a=0.998 2) models, we estimate the mass of the central black hole of this blazar. We obtain black hole masses of 1.11×10⁹M_⊙ (Schwarzschild black hole) and 7.07×10⁹M_⊙ (extreme Kerr black hole) with a main period of 7.4 days.