Optical quasi-periodic oscillations in the TESS light curves of three blazars

Abstract

ABSTRACT We report the time series analysis of Transiting Exoplanet Survey Satellite light curves of three blazars, BL Lacertae (BL Lac), 1RXS J111741.0+254858, and 1RXS J004519.6+212735, obtained using a customized approach for extracting active galactic nucleus light curves. We find tentative evidence for quasi-periodic oscillations (QPOs) in these light curves that range from 2 to 6 d. Two methods of analysis are used for assessing their significance: generalized Lomb–Scargle periodograms and weighted wavelet Z-transforms. The different approaches of these methods together ensure a robust measurement of the significance of the claimed periodicities. We can attribute the apparent QPOs to the kink instability model, which postulates that the observed QPOs are related to the temporal growth of kinks in the magnetized relativistic jet. We confirm the application of this model to BL Lac and extend the kink instability model to the other two BL Lac objects.