  The maximum likelihood estimator is used to determine fit parameters for
various parametric models of the Fourier periodogram followed by the selection
of the best fit model amongst competing models using the Akaike information
criteria. This analysis, when applied to light curves of active galactic nuclei
can be used to infer the presence of quasi-periodicity and break or knee
frequencies. The extracted information can be used to place constraints on the
mass, spin and other properties of the putative central black hole and the
region surrounding it through theoretical models involving disk and jet
physics.
