A1 Refereed original research article in a scientific journal
A multifrequency study of sub-parsec jets with the Event Horizon Telescope
Authors: Röder, J.; Wielgus, M.; Lobanov, A.P.; Krichbaum, T.P.; Nair, D.G.; Lee, S.S.; Ros, E.; Fish, V.L.; Blackburn, L.; Chan, C.K.; Issaoun, S.; Janssen, M.; Johnson, M.D.; Doeleman, S.S.; Bower, G.C.; Crew, G.B.; Tilanus, R.P.J.; Savolainen, T.; Violette Impellizzeri, C.M.; Alberdi, A.; Baczko, A.K.; Gómez, J.L.; Lu, R.S.; Paraschos, G.F.; Traianou, E.; Goddi, C.; Kim, D.; Lisakov, M.; Kovalev, Y.Y.; Voitsik, P.A.; Sokolovsky, K.V.; Akiyama, K.; Albentosa-Ruíz, E.; Alef, W.; Algaba, J.C.; Anantua, R.; Asada, K.; Azulay, R.; Bach, U.; Ball, D.; Baloković, M.; Bandyopadhyay, B.; Barrett, J.; Bauböck, M.; Benson, B.A.; Bintley, D.; Blundell, R.; Bouman, K.L.; Bremer, M.; Brinkerink, C.D.; Brissenden, R.; Britzen, S.; Broderick, A.E.; Broguiere, D.; Bronzwaer, T.; Bustamante, S.; Byun, D.Y.; Carlstrom, J.E.; Ceccobello, C.; Chael, A.; Chang, D.O.; Chatterjee, K.; Chatterjee, S.; Chen, M.T.; Chen, Y.; Cheng, X.; Cho, I.; Christian, P.; Conroy, N.S.; Conway, J.E.; Cordes, J.M.; Crawford, T.M.; Cruz-Osorio, A.; Cui, Y.; Curd, B.; Dahale, R.; Davelaar, J.; De Laurentis, M.; Deane, R.; Dempsey, J.; Desvignes, G.; Dexter, J.; Dhruv, V.; Dihingia, I.K.; Dougall, S.T.; Dzib, S.A.; Eatough, R.P.; Emami, R.; Falcke, H.; Farah, J.; Fomalont, E.; Alyson Ford, H.; Foschi, M.; Fraga-Encinas, R.; Freeman, W.T.; Friberg, P.; Fromm, C.M.; Fuentes, A.; Galison, P.; Gammie, C.F.; García, R.; Gentaz, O.; Georgiev, B.; Gold, R.; Gómez-Ruiz, A.I.; Gu, M.; Gurwell, M.; Hada, K.; Haggard, D.; Haworth, K.; Hecht, M.H.; Hesper, R.; Heumann, D.; Ho, L.C.; Ho, P.; Honma, M.; Huang, C.W.L.; Huang, L.; Hughes, D.H.; Ikeda, S.; Inoue, M.; James, D.J.; Jannuzi, B.T.; Jeter, B.; Jiang, W.; Jiménez-Rosales, A.; Jorstad, S.; Joshi, A.V.; Jung, T.; Karami, M.; Karuppusamy, R.; Kawashima, T.; Keating, G.K.; Kettenis, M.; Kim, D.J.; Kim, J.Y.; Kim, J.; Kim, J.; Kino, M.; Yi Koay, J.; Kocherlakota, P.; Kofuji, Y.; Koyama, S.; Kramer, C.; Kramer, J.A.; Kramer, M.; Kuo, C.Y.; La Bella, N.; Lauer, T.R.; Lee, D.; Leung, P.K.; Levis, A.; Li, Z.; Lico, R.; Lindahl, G.; Lindqvist, M.; Liu, J.; Liu, K.; Liuzzo, E.; Lo, W.P.; Loinard, L.; Lonsdale, C.J.; Lowitz, A.E.; Macdonald, N.R.; Mao, J.; Marchili, N.; Markoff, S.; Marrone, D.P.; Marscher, A.P.; Martí-Vidal, I.; Matsushita, S.; Matthews, L.D.; Medeiros, L.; Menten, K.M.; Michalik, D.; Mizuno, I.; Mizuno, Y.; Moran, J.M.; Moriyama, K.; Moscibrodzka, M.; Mulaudzi, W.; Müller, C.; Müller, H.; Mus, A.; Musoke, G.; Myserlis, I.; Nadolski, A.; Nagai, H.; Nagar, N.M.; Nakamura, M.; Narayanan, G.; Natarajan, I.; Nathanail, A.; Navarro Fuentes, S.; Neilsen, J.; Neri, R.; Ni, C.; Noutsos, A.; Nowak, M.A.; Oh, J.; Okino, H.; Olivares Sánchez, H.R.; Ortiz-León, G.N.; Oyama, T.; Özel, F.; Palumbo, D.C.M.; Park, J.; Parsons, H.; Patel, N.; Pen, U.L.; Pesce, D.W.; Piétu, V.; Plambeck, R.; Popstefanija, A.; Porth, O.; Pötzl, F.M.; Prather, B.; Preciado-López, J.A.; Principe, G.; Psaltis, D.; Pu, H.Y.; Ramakrishnan, V.; Rao, R.; Rawlings, M.G.; Ricarte, A.; Ripperda, B.; Roelofs, F.; Rogers, A.; Romero-Cañizales, C.; Roshanineshat, A.; Rottmann, H.; Roy, A.L.; Ruiz, I.; Ruszczyk, C.; Rygl, K.L.J.; Sánchez, S.; Sánchez-Argüelles, D.; Sánchez-Portal, M.; Sasada, M.; Satapathy, K.; Peter Schloerb, F.; Schonfeld, J.; Schuster, K.F.; Shao, L.; Shen, Z.; Small, D.; Sohn, B.W.; Soohoo, J.; Sosapanta Salas, L.D.; Souccar, K.; Stanway, J.S.; Sun, H.; Tazaki, F.; Tetarenko, A.J.; Tiede, P.; Titus, M.; Torne, P.; Toscano, T.; Trent, T.; Trippe, S.; Turk, M.; Van Bemmel, I.; Van Langevelde, H.J.; Van Rossum, D.R.; Vos, J.; Wagner, J.; Ward-Thompson, D.; Wardle, J.; Washington, J.E.; Weintroub, J.; Wharton, R.; Wiik, K.; Witzel, G.; Wondrak, M.F.; Wong, G.N.; Wu, Q.; Yadlapalli, N.; Yamaguchi, P.; Yfantis, A.; Yoon, D.; Young, A.; Young, K.; Younsi, Z.; Yu, W.; Yuan, F.; Yuan, Y.F.; Zensus, J.A.; Zhang, S.; Zhao, G.Y.; Zhao, S.S.
Publisher: EDP Sciences
Publication year: 2025
Journal: Astronomy and Astrophysics
Journal name in source: Astronomy and Astrophysics
Article number: A233
Volume: 695
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202452600
Web address : https://doi.org/10.1051/0004-6361/202452600
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/492147092
Context. The 2017 observing campaign of the Event Horizon Telescope (EHT) delivered the first very long baseline interferometry (VLBI) images at the observing frequency of 230 GHz, leading to a number of unique studies on black holes and relativistic jets from active galactic nuclei (AGN). In total, eighteen sources were observed, including the main science targets, Sgr A∗ and M87, and various calibrators. Sixteen sources were AGN.
Aims.We investigated the morphology of the sixteen AGN in the EHT 2017 data set, focusing on the properties of the VLBI cores: size, flux density, and brightness temperature. We studied their dependence on the observing frequency in order to compare it with the Blandford-Konigl (BK) jet model. In particular, we aimed to study the signatures of jet acceleration and magnetic energy conversion.
Methods. We modeled the source structure of seven AGN in the EHT 2017 data set using linearly polarized circular Gaussian components (1749+096, 1055+018, BL Lac, J0132-1654, J0006-0623, CTA102, and 3C 454.3) and collected results for the other nine AGN from dedicated EHT publications, complemented by lower frequency data in the 2-86 GHz range. Combining these data into a multifrequency EHT+ data set, we studied the dependences of the VLBI core component flux density, size, and brightness temperature on the frequency measured in the AGN host frame (and hence on the distance from the central black hole), characterizing them with power law fits. We compared the observations with the BK jet model and estimated the magnetic field strength dependence on the distance from the central black hole.
Results. Our observations spanning event horizon to parsec scales indicate a deviation from the standard BK model, particularly in the decrease of the brightness temperature with the observing frequency. Only some of the discrepancies may be alleviated by tweaking the model parameters or the jet collimation profile. Either bulk acceleration of the jet material, energy transfer from the magnetic field to the particles, or both are required to explain the observations. For our sample, we estimate a general radial dependence of the Doppler factor δ ∝ r≤0.5. This interpretation is consistent with a magnetically accelerated sub-parsec jet. We also estimate a steep decrease of the magnetic field strength with radius B ∝ r-3, hinting at jet acceleration or efficient magnetic energy dissipation.
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Funding information in the publication:
National Aeronautics and Space Administration
Universities of Bonn and Cologne
VLBA-BU
International Max Planck Research School for Environmental, Cellular and Molecular Microbiology, IMPRS-Mic
Severo Ochoa, CEX2021-001131-S, MCIN/AEI/10.13039/501100011033