No Evidence for Periodic Variability in the Light Curve of Active Galaxy J0045+41

Dorn-Wallenstein, Levesque, & Ruan recently presented the identification of a z=0.215 active galaxy located behind M31 and claimed the detection of multiple periodic variations in the object's light curve with as many as nine different periods. They interpreted these results as evidence for the presence of a binary supermassive black hole with an orbital separation of just a few hundred AU, and estimated the gravitational-wave signal implied by such a system. We demonstrate that the claimed periodicities are based on a misinterpretation of the null hypothesis test simulations and an error in the method used to calculate the false alarm probabilities. There is no evidence for periodicity in the data.
6 pages. Accepted for publication in ApJ. This paper is a comment on Dorn-Wallenstein et al. 2017, ApJ 850:86 (arXiv:1704.08694)