  We present a test of the emission statistics of active galactic nuclei (AGN),
probing the connection between red-noise temporal power spectra and multi-modal
flux distributions known from observations. We simulate AGN lightcurves under
the assumption of uniform stochastic emission processes for different power-law
indices of their power spectra. For sufficiently shallow slopes (power-law
indices beta < 1), the flux distributions (histograms) of the resulting
lightcurves are approximately Gaussian. For indices corresponding to steeper
slopes (beta > 1), the flux distributions become multi-modal. This finding
disagrees systematically with results of recent mm/radio observations.
Accordingly, we conclude that the emission from AGN does not necessarily
originate from uniform stochastic processes even if their power spectra suggest
this. Possible mechanisms are transitions between different activity states
and/or the presence of multiple, spatially disconnected, emission regions.
