Periods of the Long-Term Variability of the Blazar 0716+714 and Their Inter-Correlations in a Helical Jet Model

Abstract: Various quasi-periods for the long-term variability of the radio emission, optical emission, and structural position angle of the inner part of the parsec-scale jet in the blazar 0716+714 have been detected. The relationships between these quasi-periods are interpreted assuming that the variability arises due to a helical structure of the jet, which is preserved from regions near the jet base to at least 1 milliarcsecond from the core observed in radio interferometric observations. The radiating jet components should display radial motions with Lorentz factors of $\approx3$, and decelerate with distance from the jet base. The best agreement with the data is given in the case of non-radial motions of these components with a constant physical speed. It is also shown that the helical shape of the jet strongly influences correlations both between fluxes observed in different spectral ranges and between the flux and position angle of the inner part of the parsec-scale jet.