Resolving the Inner Parsec of the Blazar J1924-2914 with the Event Horizon Telescope

Sara Issaoun*, Maciek Wielgus, Svetlana Jorstad, Thomas P. Krichbaum, Lindy Blackburn, Michael Janssen, Chi-kwan Chan, Dominic W. Pesce, Jose L. Gomez, Kazunori Akiyama, Monika Moscibrodzka, Ivan Marti-Vidal, Andrew Chael, Rocco Lico, Jun Liu, Venkatessh Ramakrishnan, Mikhail Lisakov, Antonio Fuentes, Guang-Yao Zhao, Kotaro MoriyamaAvery E. Broderick, Paul Tiede, Nicholas R. MacDonald, Yosuke Mizuno, Efthalia Traianou, Laurent Loinard, Jordy Davelaar, Mark Gurwell, Ru-Sen Lu, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Richard Anantua, Keiichi Asada, Rebecca Azulay, Uwe Bach, Anne-Kathrin Baczko, David Ball, Mislac Balokovic, John Barrett, Michi Baubock, Bradford A. Benson, Dan Bintley, Raymond Blundell, Wilfred Boland, Katherine L. Bouman, Geoffrey C. Bower, Dong-Jin Kim, Tuomas Savolainen, Jan Wagner, Event Horizon Telescope Collaboration

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

23 Citations (Scopus)
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The blazar J1924–2914 is a primary Event Horizon Telescope (EHT) calibrator for the Galactic center’s black hole Sagittarius A *. Here we present the first total and linearly polarized intensity images of this source obtained with the unprecedented 20 µas resolution of the EHT. J1924–2914 is a very compact flat-spectrum radio source with strong optical variability and polarization. In April 2017 the source was observed quasi-simultaneously with the EHT (April 5–11), the Global Millimeter VLBI Array (April 3), and the Very Long Baseline Array (April 28), giving a novel view of the source at four observing frequencies, 230, 86, 8.7, and 2.3 GHz. These observations probe jet properties from the subparsec to 100 pc scales. We combine the multifrequency images of J1924–2914 to study the source morphology. We find that the jet exhibits a characteristic bending, with a gradual clockwise rotation of the jet projected position angle of about 90° between 2.3 and 230 GHz. Linearly polarized intensity images of J1924–2914 with the extremely fine resolution of the EHT provide evidence for ordered toroidal magnetic fields in the blazar compact core.

Original languageEnglish
Article number145
Number of pages21
JournalThe Astrophysical Journal
Issue number2
Publication statusPublished - 1 Aug 2022
MoE publication typeA1 Journal article-refereed


  • VLBI
  • M87


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