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 ( AGN ) , one of our sample of 21 AGN 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 can not be ruled out .
From optical spectroscopy , we measure the black hole mass of this AGN as log ( M _ { \mathrm { BH } } / M _ { \odot } ) = 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 AGN , similar to the known correlation in high-frequency QPOs .