Multiwavelength behaviour of the blazar 3C 279: decade-long study from γ-ray to radio

Larionov, V. M.; Jorstad, S. G.; Marscher, A. P.; Villata, M.; Raiteri, C. M.; Smith, P. S.; Agudo, I.; Savchenko, S. S.; Morozova, D. A.; Acosta-Pulido, J. A.; Aller, M. F.; Aller, H. D.; Andreeva, T. S.; Arkharov, A. A.; Bachev, R.; Bonnoli, G.; Borman, G. A.; Bozhilov, V.; Calcidese, P.; Carnerero, M. I.; Carosati, D.; Casadio, C.; Chen, W. -P.; Damljanovic, G.; Dementyev, A. V.; Di Paola, A.; Frasca, A.; Fuentes, A.; Gómez, J. L.; Gónzalez-Morales, P.; Giunta, A.; Grishina, T. S.; Gurwell, M. A.; Hagen-Thorn, V. A.; Hovatta, T.; Ibryamov, S.; Joshi, M.; Kiehlmann, S.; Kim, J. -Y.; Kimeridze, G. N.; Kopatskaya, E. N.; Kovalev, Yu A.; Kovalev, Y. Y.; Kurtanidze, O. M.; Kurtanidze, S. O.; Lähteenmäki, A.; Lázaro, C.; Larionova, L. V.; Larionova, E. G.; Leto, G.; Marchini, A.; Matsumoto, K.; Mihov, B.; Minev, M.; Mingaliev, M. G.; Mirzaqulov, D.; Muñoz Dimitrova, R. V.; Myserlis, I.; Nikiforova, A. A.; Nikolashvili, M. G.; Nizhelsky, N. A.; Ovcharov, E.; Pressburger, L. D.; Rakhimov, I. A.; Righini, S.; Rizzi, N.; Sadakane, K.; Sadun, A. C.; Samal, M. R.; Sanchez, R. Z.; Semkov, E.; Sergeev, S. G.; Sigua, L. A.; Slavcheva-Mihova, L.; Sola, P.; Sotnikova, Yu V.; Strigachev, A.; Thum, C.; Traianou, E.; Troitskaya, Yu V.; Troitsky, I. S.; Tsybulev, P. G.; Vasilyev, A. A.; Vince, O.; Weaver, Z. R.; Williamson, K. E.; Zhekanis, G. V.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society

Advertised on:
3
2020
Number of authors
87
IAC number of authors
4
Citations
40
Refereed citations
39
Description
We report the results of decade-long (2008-2018) γ-ray to 1 GHz radio monitoring of the blazar 3C 279, including GASP/WEBT, Fermi and Swift data, as well as polarimetric and spectroscopic data. The X-ray and γ-ray light curves correlate well, with no delay ≳ 3 h, implying general cospatiality of the emission regions. The γ-ray-optical flux-flux relation changes with activity state, ranging from a linear to a more complex dependence. The behaviour of the Stokes parameters at optical and radio wavelengths, including 43 GHz Very Long Baseline Array images, supports either a predominantly helical magnetic field or motion of the radiating plasma along a spiral path. Apparent speeds of emission knots range from 10 to 37c, with the highest values requiring bulk Lorentz factors close to those needed to explain γ-ray variability on very short time-scales. The Mg II emission line flux in the `blue' and `red' wings correlates with the optical synchrotron continuum flux density, possibly providing a variable source of seed photons for inverse Compton scattering. In the radio bands, we find progressive delays of the most prominent light-curve maxima with decreasing frequency, as expected from the frequency dependence of the τ = 1 surface of synchrotron self-absorption. The global maximum in the 86 GHz light curve becomes less prominent at lower frequencies, while a local maximum, appearing in 2014, strengthens toward decreasing frequencies, becoming pronounced at ̃5 GHz. These tendencies suggest different Doppler boosting of stratified radio-emitting zones in the jet.
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