Multiwavelength behaviour of the blazar 3C 279: decade-long study from γ-ray to radio. Issue 3 (11th January 2020)

• Record Type: Journal Article
• Authors: 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;
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 492:Issue 3(2020)
• Page Start: 3829
• Page End: 3848
• Publication Date: 2020-01-11
• Subjects: methods: observational -- techniques: photometric -- techniques: polarimetric -- techniques: spectroscopic -- galaxies: active -- quasars: individual: 3C 279; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa082
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: 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 $\gtrsim 3$ 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.