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The advent of new time domain surveys and the imminent increase inastronomical data expose the shortcomings in traditional time series analysis(such as power spectra analysis) in characterising the abundantly varied,complex and stochastic light curves of Active Galactic Nuclei (AGN). Recentapplications of novel methods from non-linear dynamics have shown promise incharacterising higher modes of variability and time-scales in AGN. Recurrenceanalysis in particular can provide complementary information aboutcharacteristic time-scales revealed by other methods, as well as probe thenature of the underlying physics in these objects. Recurrence analysis wasdeveloped to study the recurrences of dynamical trajectories in phase space,which can be constructed from one-dimensional time series such as light curves.We apply the methods of recurrence analysis to two optical light curves ofKepler-monitored AGN. We confirm the detection and period of an opticalquasi-periodic oscillation in one AGN, and confirm multiple other time-scalesrecovered from other methods ranging from 5 days to 60 days in both objects. Wedetect regions in the light curves that deviate from regularity, provideevidence of determinism and non-linearity in the mechanisms underlying onelight curve (KIC 9650712), and determine a linear stochastic process recoversthe dominant variability in the other light curve (Zwicky 229--015). We discusspossible underlying processes driving the dynamics of the light curves andtheir diverse classes of variability.

Complex Variability of Kepler AGN Revealed by Recurrence Analysis