Evidence for an Optical Low-frequency Quasi-periodic Oscillation in the Kepler Light Curve of an Active Galaxy

We report evidence for a quasi-periodic oscillation (QPO) in the optical light curve of KIC. 9650712, a narrow-line Seyfert 1 galaxy in the original Kepler field. After the development and application of a pipeline for Kepler data specific to active galactic nuclei (AGNs), one of our sample of 21 AGNs selected by infrared photometry and X-ray flux demonstrates a peak in the power spectrum at log nu = -6.58 Hz, corresponding to a temporal period of t - 44 days. We note that although the power spectrum is well fit by a model consisting of a Lorentzian and a single power law, alternative continuum models cannot be ruled out. From optical spectroscopy, we measure the black hole mass of this AGN as log. (M-BH/M-circle dot) - 8.17. We find that this frequency lies along a correlation between low-frequency QPOs and black hole mass from stellar and intermediate mass black holes to AGNs, similar to the known correlation in high-frequency QPOs.