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Multiwavelength quasi-periodic variability of the blazar Ton 599

Yu. V. Sotnikova, T. V. Mufakharov, A. E. Volvach, V. V. Vlasyuk, M. L. Khabibullina, A. G. Mikhailov, T. An, D. O. Kudryavtsev, Yu. A. Kovalev, Y. Y. Kovalev, A. V. Popkov, S. S. Savchenko, A. K. Erkenov, D. A. Morozova, T. A. Semenova, O. I. Spiridonova, M. A. Kharinov, I. A. Rakhimov, T. S. Andreeva, L. Cui, X. Wang, N. Chang, R. Yu. Udovitskiy, P. G. Zhekanis, G. A. Borman, T. S. Grishina, E. N. Kopatskaya, E. G. Larionova, I. S. Troitskiy, Yu. V. Troitskaya, A. A. Vasilyev, A. V. Zhovtan, D. V. Kratov, L. N. Volvach, E. V. Shishkina, A. I. Dmytrotsa, V. I. Zharov

Abstract

During the last 40-50 years, the TeV blazar Ton 599 has systematically experienced major outbursts detected in a wide wavelength range from radio to $γ$-rays. In this work, we present an analysis of Ton 599 quasi-periodic variability across multiple wavelengths using an observing baseline from 1983 to 2025. The $γ$-ray, optical, and radio emissions are found to be highly correlated with time lags $\sim0$-$360$ days, which indicates that they are triggered by the same population of particles. Using the Lomb-Scargle periodogram and the Weighted Wavelet Z-transform, we revealed several periodic components with characteristic periods of 1.4, 1.7, 2.3, 6.5, and 7.5 yrs. The result is consistent with the detection of periodic components in the 1997-2011 light curves, which means that we observe the same mechanism causing long-term periodic variability. A model of a binary supermassive black hole (SMBH) with a precessing jet, applied to the radio light curves of Ton 599, yields frequency-dependent best-fitting parameters with orbital periods ranging from $\sim$1.2 to 1.7 yrs and precession periods from $\sim$5.8 to 7.7 yrs. This result implies the existence of an SMBH system modulating emission through both the orbiting and jet precession effects, with differing observed periods possibly reflecting frequency-dependent emission regions along a structured, stratified jet. Nonetheless, the short-term periodicity and exceptionally strong flares likely arise from internal jet shocks, which aligns with typical blazar behavior. We suggest that the multiband quasi-periodicity of Ton 599 is reasonably described by a combination of geometric effects (orbital motion and precession) and stochastic processes.

Multiwavelength quasi-periodic variability of the blazar Ton 599

Abstract

During the last 40-50 years, the TeV blazar Ton 599 has systematically experienced major outbursts detected in a wide wavelength range from radio to -rays. In this work, we present an analysis of Ton 599 quasi-periodic variability across multiple wavelengths using an observing baseline from 1983 to 2025. The -ray, optical, and radio emissions are found to be highly correlated with time lags - days, which indicates that they are triggered by the same population of particles. Using the Lomb-Scargle periodogram and the Weighted Wavelet Z-transform, we revealed several periodic components with characteristic periods of 1.4, 1.7, 2.3, 6.5, and 7.5 yrs. The result is consistent with the detection of periodic components in the 1997-2011 light curves, which means that we observe the same mechanism causing long-term periodic variability. A model of a binary supermassive black hole (SMBH) with a precessing jet, applied to the radio light curves of Ton 599, yields frequency-dependent best-fitting parameters with orbital periods ranging from 1.2 to 1.7 yrs and precession periods from 5.8 to 7.7 yrs. This result implies the existence of an SMBH system modulating emission through both the orbiting and jet precession effects, with differing observed periods possibly reflecting frequency-dependent emission regions along a structured, stratified jet. Nonetheless, the short-term periodicity and exceptionally strong flares likely arise from internal jet shocks, which aligns with typical blazar behavior. We suggest that the multiband quasi-periodicity of Ton 599 is reasonably described by a combination of geometric effects (orbital motion and precession) and stochastic processes.
Paper Structure (28 sections, 23 equations, 44 figures, 15 tables)

This paper contains 28 sections, 23 equations, 44 figures, 15 tables.

Table of Contents

  1. Introduction
  2. Observed data
  3. RATAN-600
  4. RT-32
  5. RT-22
  6. NSRT
  7. Optical data
  8. Fermi-LAT
  9. Long-term light curves
  10. Cross-correlation between the light curves
  11. Search for quasi-periodicity
  12. Lomb--Scargle periodogram
  13. Weighted wavelet Z-transform
  14. Physical driving mechanisms
  15. Lense--Thirring precession
  16. ...and 13 more sections

Figures (44)

  • Figure 1: Multiband light curves of Ton 599 in 1997--2025.
  • Figure 2: The 22 and 37 GHz radio light curves of Ton 599 measured with the RT-22 and RATAN-600 in 1983--2025.
  • Figure 3: Multiband fractional variability in different epochs.
  • Figure 4: Lags of the light curves at various frequencies ($\log_{10} \nu$) with respect to the light curve at a frequency of 37 GHz (the zero lag marked by the grey lines). The frequency range is from 2 GHz (the leftmost points) to the optical $R$ band (on the right). The epochs are shown by different colors.
  • Figure 5: The LS periodograms for the total flux variations at 2, 5, 8, 11, 22, 37, 230 GHz, in the optical $R$ band, and in $\gamma$-rays. The dashed blue and red lines show the false alarm probability levels ${\rm FAP} =1$ and $5$ per cent.
  • ...and 39 more figures