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arXiv · 2606.25868

Broadband multiwavelength properties of the archetypal blazar 3C 279 during the 2017 Event Horizon Telescope campaign

G. Principe·J. C. Algaba·E. Aviano·W. Y. Cheong·K. Hada·D. Haggard·A. Hahn·S. G. Jorstad·E. V. Kravchenko·Y. Kovalev·S. S. Lee·M. Lisakov·S. Markoff·A. P. Marscher·M. Sasada·P. Voitsik·Kazunori Akiyama·Ezequiel Albentosa-Ruiz·Antxon Alberdi·Walter Alef·Richard Anantua·Eleni Antonopoulou·Keiichi Asada·Rebecca Azulay·Anne-Kathrin Baczko·David Ball·Bidisha Bandyopadhyay·John Barrett·Michi Baubock·Bradford A. Benson·Dan Bintley·Lindy Blackburn·Raymond Blundell·Katherine L. Bouman·Geoffrey C. Bower·Michael Bremer·Roger Brissenden·Silke Britzen·Avery E. Broderick·Dominique Broguiere·Thomas Bronzwaer·Sandra Bustamante·Douglas F. Carlos·John E. Carlstrom·Andrew Chael·Chi-kwan Chan·Dominic O. Chang·Koushik Chatterjee·Ming-Tang Chen·Yongjun Chen·Xiaopeng Cheng·Paul Chichura·Ilje Cho·Nicholas S. Conroy·John E. Conway·Thomas M. Crawford·Geoffrey B. Crew·Alejandro Cruz-Osorio·Yuzhu Cui·Brandon Curd·Rohan Dahale·Jordy Davelaar·Joost de Kleuver·Mariafelicia De Laurentis·Roger Deane·Jason Dexter·Vedant Dhruv·Indu K. Dihingia·Sheperd S. Doeleman·Sergio A. Dzib·Razieh Emami·Heino Falcke·Joseph Farah·Vincent L. Fish·Edward Fomalont·H. Alyson Ford·Marianna Foschi·Raquel Fraga-Encinas·William T. Freeman·Per Friberg·Christian M. Fromm·Antonio Fuentes·Peter Galison·Charles F. Gammie·Roberto Garcia·Olivier Gentaz·Boris Georgiev·Ciriaco Goddi·Roman Gold·Arturo I. Gomez-Ruiz·Jose L. Gomez·Minfeng Gu·Mark Gurwell·Ronald Hesper·Dirk Heumann·Luis C. Ho·Paul Ho·Mareki Honma·Chih-Wei L. Huang·Lei Huang

Abstract

The archetypal blazar 3C 279 hosts a prominent relativistic jet and exhibits strong broadband variability across the electromagnetic spectrum. In April 2017, the Event Horizon Telescope (EHT) observed 3C 279, alongside one of the most extensive quasi-simultaneous multiwavelength (MWL) campaigns ever conducted. With the aim of investigating the physical processes governing 3C 279, we analyzed individual observations and multiband light curves, and constructed a new quasi-simultaneous MWL spectrum. We also performed phenomenological modeling using the turbulent extreme multi-zone (TEMZ) model to constrain the fundamental physical properties of the source. The EHT observations reveal a clear flux increase in the innermost core between April 5 and 11, 2017. Over a broader timescale, radio measurements at longer wavelengths show concurrent enhancements in core flux and polarization around mid-April, coinciding with the ejection of a superluminal knot. Record UV-optical flares with strong polarization variability occurred in late March, followed by gamma-ray activity that declined before the end of the EHT observing period. During this interval, the source remained in a low X-ray state and showed no detectable VHE emission. The TEMZ modeling suggests that the broadband spectrum and variability of 3C 279 can be explained within a jet scenario in which turbulent plasma cells are compressed by a stationary conical shock. However, alternative interpretations, such as magnetic reconnection or a moving shock-in-jet event, remain plausible. This coordinated MWL campaign advances our understanding of the origin of jet and gamma-ray emission in 3C 279, while also providing a comprehensive publicly available dataset that will serve as a valuable reference for future studies.

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G. Principe, J. C. Algaba, E. Aviano, W. Y. Cheong, K. Hada, D. Haggard, A. Hahn, S. G. Jorstad, E. V. Kravchenko, Y. Kovalev, S. S. Lee, M. Lisakov, S. Markoff, A. P. Marscher, M. Sasada, P. Voitsik, Kazunori Akiyama, Ezequiel Albentosa-Ruiz, Antxon Alberdi, Walter Alef, Richard Anantua, Eleni Antonopoulou, Keiichi Asada, Rebecca Azulay, Anne-Kathrin Baczko, David Ball, Bidisha Bandyopadhyay, John Barrett, Michi Baubock, Bradford A. Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Katherine L. Bouman, Geoffrey C. Bower, Michael Bremer, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Douglas F. Carlos, John E. Carlstrom, Andrew Chael, Chi-kwan Chan, Dominic O. Chang, Koushik Chatterjee, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Paul Chichura, Ilje Cho, Nicholas S. Conroy, John E. Conway, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Brandon Curd, Rohan Dahale, Jordy Davelaar, Joost de Kleuver, Mariafelicia De Laurentis, Roger Deane, Jason Dexter, Vedant Dhruv, Indu K. Dihingia, Sheperd S. Doeleman, Sergio A. Dzib, Razieh Emami, Heino Falcke, Joseph Farah, Vincent L. Fish, Edward Fomalont, H. Alyson Ford, Marianna Foschi, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Charles F. Gammie, Roberto Garcia, Olivier Gentaz, Boris Georgiev, Ciriaco Goddi, Roman Gold, Arturo I. Gomez-Ruiz, Jose L. Gomez, Minfeng Gu, Mark Gurwell, Ronald Hesper, Dirk Heumann, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang. 2026-06-24. Broadband multiwavelength properties of the archetypal blazar 3C 279 during the 2017 Event Horizon Telescope campaign. https://arxiv.org/abs/2606.25868

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