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Revisiting 3C 279 jet morphology with space VLBI at 26 microarcsecond resolution

We present observations of the blazar 3C 279 at 22 GHz by the space-based very long baseline interferometry mission RadioAstron from January 15, 2018. We reconstructed images in both total intensity and fractional polarization using the regularized maximum likelihood method implemented in the eht-im...

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Main Authors: Toscano, Teresa (Author) , Gómez, José L. (Author) , Zhao, Guang-Yao (Author) , Lico, Rocco (Author) , Fuentes, Antonio (Author) , Savolainen, Tuomas (Author) , Röder, Jan (Author) , Wielgus, Maciek (Author) , Pushkarev, Alexander B. (Author) , Traianou, Efthalia (Author) , Zeng, Ai-Ling (Author) , Gurvits, Leonid I. (Author) , Kovalev, Yuri Y. (Author) , Pötzl, Felix M. (Author) , Lisakov, Mikhail (Author)
Format: Article (Journal)
Language:English
Published: December 2025
In: Astronomy and astrophysics
Year: 2025, Volume: 704, Pages: 1-12
ISSN:1432-0746
DOI:10.1051/0004-6361/202555188
Online Access:Verlag, kostenfrei, Volltext: https://doi.org/10.1051/0004-6361/202555188
Verlag, kostenfrei, Volltext: https://www.aanda.org/articles/aa/abs/2025/12/aa55188-25/aa55188-25.html
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Author Notes:Teresa Toscano, José L. Gómez, Guang-Yao Zhao, Rocco Lico, Antonio Fuentes, Tuomas Savolainen, Jan Röder, Maciek Wielgus, Alexander B. Pushkarev, Efthalia Traianou, Ai-Ling Zeng, Leonid I. Gurvits, Yuri Y. Kovalev, Felix M. Pötzl, and Mikhail Lisakov
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Summary:We present observations of the blazar 3C 279 at 22 GHz by the space-based very long baseline interferometry mission RadioAstron from January 15, 2018. We reconstructed images in both total intensity and fractional polarization using the regularized maximum likelihood method implemented in the eht-imaging library. The electric vector position angles are found to be mostly aligned with the general jet direction, suggesting a predominantly toroidal magnetic field and in agreement with the presence of a helical magnetic field. Ground-space fringes were detected up to a projected baseline length of ∼8 Gλ, achieving an angular resolution of around 26 μas. The fine-scale structure of the relativistic jet is found in our study to extend to a projected distance of ∼180 parsec from the radio core. However, the filamentary structure reported by previous RadioAstron observations from 2014 is not detected in our current study. We discuss potential causes for this phenomenon and present a comparison using public 43 GHz data from the BEAM-ME program showing a significant drop in the jet’s total intensity. We observe that the optically thick core has a brightness temperature of 1.6 × 10<sup>12<sup/> K, consistent with equipartition between the energy densities of the relativistic particles and the magnetic field. This yields an estimated magnetic field strength of 0.2 G.
Item Description:Online veröffentlicht: 12. Dezember 2025
Gesehen am 19.02.2026
Physical Description:Online Resource
ISSN:1432-0746
DOI:10.1051/0004-6361/202555188

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