Physical Characteristics of the Blazar AO 0235+164

Long series of multi-frequency monitoring data of the active galactic nucleus (AGN) AO 0235+164 from the radio to the gamma-ray are analyzed. AO 0235+164 may be a close binary system comprised of two supermassive black holes (SMBHs). A harmonic analysis has established the presence of orbital and precessional periods of two and eight years, respectively. These values are close to the analogous periods found in other AGNs that have been proposed to be close SMBH binary systems in a stage of their evolution close to coalescence. A cross-correlation analysis is used to find the time delay between corresponding flares occurring in different wavebands. The empirical dependence found earlier for a number of other AGNS relating the delay in the flux variations with the frequency is observed for this object, and has the form of an inverse logarithmic dependence, providing evidence that the flux variability of AGNs at centimeter and shorter wavelengths is intrinsic. The standard picture of jet activity of AGNs supposes plasma formations that move from the central regions along outflows, becoming optically thin at longer and longer wavelengths as they do so. The physical and dynamical characteristics of AO 0235+164 suggest it is a close binary with SMBHs with similar masses of the order of 10(10)M(circle dot). This is one of the most massive systems of two SMBHs. The velocities of the companion and central black hole about their common center of mass are estimated to be 10(4) and 5 x 10(3) km/s. The results obtained suggest that observed bright AGNs form a relatiavely rare population among massive elliptical galaxies, due to their narrowly directed emission and their short lifetimes.