Detecting periodic signatures in red-noise dominated lightcurves of accreting black holes

Music City Center 

Emission of matter accreted on black holes (BHs) in active galactic nuclei (AGN) shows variability across the electromagnetic spectrum. Radio to gamma-ray band power spectral densities (PSDs) of AGN time-series are dominated by stochastic broadband noise typically modeled well with a Damped Random Walk or power-law functions. However, ongoing efforts have identified an increasing number of AGN candidates, for which a (quasi-)periodic PSD component appears to be statistically significant. AGN whose light show strong periodic modulations have become widely recognized as candidate BH binaries. Such binaries are a natural consequence of hierarchical structure formation, where galaxies grow via mergers. This talk will review efforts to characterize multi-wavelength AGN variability, including periodicities, in time domain with the Continuous-time Auto-Regressive Moving Average approaches, CARMA. Caveats related to non-stationary AGN time series, as well as novel avenues to overcome them, will be discussed in the light of anticipated massive single and binary AGN datasets from sky surveys delivered by observatories like Vera Rubin and others.