Quasi-periodic behaviour in the radio and -ray light curves of blazar PKS 1510-089

We explore the possible quasi-periodic oscillations (QPOs) of the blazar PKS 1510-089, utilizing the similar to 38-yr Metsahovi flux density observations at 37 GHz and over 10-yr Fermi Large Area Telescope observations in the 0.1-300 GeV energy range. Both the flux distributions of the radio and gamma-ray light curves suggest a lognormal distribution, and power spectral densities of both light curves can be well represented by a bending power-law model. Comparing the results from the weighted wavelet Z-transform and Lomb-Scargle periodogram approaches, a quasi-period of 1330 +/- 55 d at a 99.80 percent (>3 sigma) significance against the red noise background is observed in the radio light curve, whereas no similar modulation is seen in the gamma-ray light curve. We briefly discuss the research actuality of blazar QPO phenomena and explain the observed radio QPO as the result of Keplerian motion in a supermassive binary black hole system and periodic modulation induced by the Lense-Thirring precession of the innermost portions of the accretion disc.