Horizon-scale variability of M87* from 2017–2021 EHT observations

We report three epochs of polarized images of M87* at 230 GHz using data from the Event Horizon Telescope (EHT) taken in 2017, 2018, and 2021. The baseline coverage of the 2021 observations is significantly improved through the addition of two new EHT stations: the 12 m Kitt Peak Telescope and the Northern Extended Millimetre Array (NOEMA). All observations result in images dominated by a bright, asymmetric ring with a persistent diameter of 43.9 ± 0.6 μas, consistent with expectations for lensed synchrotron emission encircling the apparent shadow of a supermassive black hole. We find that the total intensity and linear polarization of M87* vary significantly across the three epochs. Specifically, the azimuthal brightness distribution of the total intensity images varies from year to year, as expected for a stochastic accretion flow. However, despite a gamma-ray flare erupting in M87 quasi-contemporaneously to the 2018 observations, the 2018 and 2021 images look remarkably similar. The resolved linear polarization fractions in 2018 and 2021 peak at ∼5%, compared to ∼15% in 2017. The spiral polarization pattern on the ring also varies from year to year, including a change in the electric vector position angle helicity in 2021 that could reflect changes in the magnetized accretion flow or an external Faraday screen. The improved 2021 coverage also provides the first EHT constraints on jet emission outside the ring, on scales of ≲1 mas. Overall, these observations provide strong proof of the reliability of the EHT images and probe the dynamic properties of the horizon-scale accretion flow surrounding M87*.

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Journal
Astronomy and Astrophysics
Published
2025-09-15
DOI
https://doi.org/10.1051/0004-6361/202555855
Citations
5
Primary Topic
Astrophysics and Cosmic Phenomena
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article
Field-Weighted Citation Impact
9.35
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article

Horizon-scale variability of M87* from 2017–2021 EHT observations

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5 citations
Astronomy and Astrophysics
Astrophysics and Cosmic Phenomena
9.35
article

Horizon-scale variability of M87* from 2017–2021 EHT observations

Wanga Mulaudzi, Ben Prather, Dimitrios Psaltis, Lisa Fish, Chunchong Ni, Laura Gómez, Chi‐kwan Chan, Richard Anantua, Paul Yamaguchi, D.M. Johnson, Doosoo Yoon, Teresa Toscano, Greg Lindahl, L. Ricci, Lia Medeiros, Gopal Narayanan, A. V. Plavin, Yuzhu Cui, S. Britzen, E. John Conway, Ryan Berthold, T. Savolainen, Ezequiel Albentosa-Ruíz, Saurabh Kumar, K. Wiik, Roman Gold, Monika Mościbrodzka, Xiaopeng Cheng, Angelo Ricarte, Walter Alef, Ignacio Ruiz, José Luis Hernández-Rebollar, D. Ward–Thompson, Des Small, Kenji Toma, Tomohisa Kawashima, Michaël Janssen, He Sun, Shoko Koyama, Ronald Hesper, Sandra Bustamante, A. Joana Kramer, Makoto Inoue, S. Joshua Stanway, A. Alberdi, Jesse Vos, Britton Jeter, Matthew Turk, Iván Rodríguez-Montoya, Paul T. P. Ho, Jordy Davelaar, Vikas Joshi, Ue‐Li Pen, Laurent Loinard, Héctor Olivares, Ilje Cho, Santiago Navarro Fuentes, Vedant Dhruv, Iniyan Natarajan, Paul Tiede, Erandi Chavez, Sheperd S. Doeleman, Sera Markoff, Prashant Kocherlakota, Kamal Souccar, Sang-Sung Lee, Michael S. Titus, Daniel Michalik, Jan Röder, Dominique Broguière, R. Blundell, Satoki Matsushita, Gunther Witzel, Jason Soohoo, Efthalia Traianou, Roy Lang, G. Principe, Ming‐Tang Chen, Izumi Mizuno, Bart Ripperda, Salvador Sánchez, Hiroki Okino, Alejandro Mus, Bong Won Sohn, Kaushik Satapathy, Cristina Romero-Cañizales, Anne-Kathrin Baczko, Bidisha Bandyopadhyay, Guang-Yao Zhao, Mark Kettenis, Luciano Rezzolla, Chad T. Palumbo, Wen-Ping Lo, John Barrett, Taehyun Jung, Peter Galison, Juan Carlos Algaba, Ilse van Bemmel, Wu Jiang, Razieh Emami, I. Myserlis, Amy Benson, Hung-Yi Pu, Kazunori Akiyama, J. A. Zensus, Motoki Kino, Aviad Levis, E. B. Fomalont, Per Friberg, Shiro Ikeda, Andrew Chael, Olivier Gentaz, Noemi La Bella, Derek Kubo, Roger Deane, Lijing Shao, C. Goddi, Ramprasad Rao, Boris Georgiev, J. F. C. Wardle, Roger Brissenden, N. George Wong, Marianna Foschi, Michi Bauböck, S. Silpa, Andrzej J. Nowak, K. Schüster, Jonathan Schonfeld, J. Montgomery, M. Sánchez‐Portal, Ziri Younsi, Huib Jan van Langevelde, P. M. Chichura, N. Marchili, Kotaro Moriyama, H. Falcke, Helen Hughes, M. Kramer, Greshma Nair, U. Bach, Shan-Shan Zhao, Mareki Honma, Arash Roshanineshat, G. Desvignes, M. Lindqvist, Jason Dexter, Chih-Chiang Han, Maciek Wielgus, Pablo Torné, Shami Chatterjee, Mariafelicia De Laurentis, Fumie Tazaki, Freek Roelofs, P. Andrei Lobanov, T. Freeman, Joseph Farah, Antonio Fuentes, Rebecca Azulay, C. Krämer, C. M. Violette Impellizzeri, Raquel Fraga-Encinas, C. Ho, Douglas Ferreira Carlos, Gibwa Musoke, Nimesh Patel, F. Charles Gammie, Andrew Nadolski, Michael Bremer, Antonios Nathanail, Kuo Liu, Thomas Bronzwaer, C. Ruszczyk, Venkatessh Ramakrishnan, Alejandra Jiménez-Rosales, Georgios Filippos Paraschos, Mahito Sasada, Eric Carlström, David Sánchez-Argüelles, Mark Gurwell, Mikhail Lisakov, Peter Oshiro, Harriet Parsons, Gertie Geertsema, Sara Issaoun, Pierre Christian, E. Ros, Katie M. Keating, Feryal Özel, Ryan Chilson, Daryl Haggard, Jan Wagner, Feng Yuan, R. Karuppusamy, A. Rahlin, Alejandro Cruz-Osorio, Koushik Chatterjee, Michael Fromm, Patrick M. Koch, Junghwan Oh, Dirk Heumann, Masanori Nakamura, Keiichi Asada, Rohan Dahale, Mislav Baloković, Deokhyeong Lee, Teddy Huang, Ai-Ling Zeng, Robert Wharton, Malhar Nagar, Elisabetta Liuzzo, O. Chang, Oliver Porth, Lindy Blackburn, Brandon Curd, Kuan‐Yu Liu, Yosuke Mizuno, R. Nicholas MacDonald, Aristomenis Yfantis, Cornelia Müller, Jae-Young Kim, Shuo Zhang, Jongho Park, Lei Huang, David Matthews, Wei Yu, Hendrik Müller, Jirong Mao, Roberto García, H. Alyson Ford, André Young, David Ball, Dan Hoak, M. Karl Menten, Joey Neilsen, F. Peter Schloerb, Randall W. Smith, Ye‐Fei Yuan, Sascha Trippe, Jongsoo Kim, Vincent Piétu, Tyler Trent, Hiroshi Nagai, C. Adam Jones, Zhiqiang Shen, Dong-Jin Kim, Yutaro Kofuji, Junhan Kim, Iván Martí-Vidal, Dan Bintley, Tomoaki Oyama, H. Rottmann, Aleksandar PopStefanija, Lei 磊 Huang 黄, Rocco Lico, Tashun Wei, E. Washington, John Lonsdale, Minfeng Gu, J. David James, Kazuhiro Hada, C. Bower, Michael E. Moran, Cheng-Yu Kuo, D.S. León Salas, Nitika Yadlapalli, Shu-Hao Chang, M. K. Crawford, Qingwen Wu, Alfredo Montaña, S. Nicholas Conroy, Jun Liu, T. Buell Jannuzi, L.J. Kazi Rygl, P. Thomas Krichbaum, E. Amy Lowitz, P. Daniel Marrone, P. Alan Marscher, W. Dominic Pesce, Mark G. Rawlings, J. Alexandra Tetarenko, R. P. J. Tilanus, R. Daniel van Rossum, G. Crew, L. Katherine Bouman, E. Avery Broderick, K. Indu Dihingia, A. Sergio Dzib, P. Ralph Eatough, I. Arturo Gómez-Ruiz, Jun Yi Koay, Zhiyuan Li, Ru-Sen Lu, D. Sebastiano von Fellenberg, Jompoj Wongphexhauxsorn, Xiaopeng Cheng
article en
5 citations

Abstract

We report three epochs of polarized images of M87* at 230 GHz using data from the Event Horizon Telescope (EHT) taken in 2017, 2018, and 2021. The baseline coverage of the 2021 observations is significantly improved through the addition of two new EHT stations: the 12 m Kitt Peak Telescope and the Northern Extended Millimetre Array (NOEMA). All observations result in images dominated by a bright, asymmetric ring with a persistent diameter of 43.9 ± 0.6 μas, consistent with expectations for lensed synchrotron emission encircling the apparent shadow of a supermassive black hole. We find that the total intensity and linear polarization of M87* vary significantly across the three epochs. Specifically, the azimuthal brightness distribution of the total intensity images varies from year to year, as expected for a stochastic accretion flow. However, despite a gamma-ray flare erupting in M87 quasi-contemporaneously to the 2018 observations, the 2018 and 2021 images look remarkably similar. The resolved linear polarization fractions in 2018 and 2021 peak at ∼5%, compared to ∼15% in 2017. The spiral polarization pattern on the ring also varies from year to year, including a change in the electric vector position angle helicity in 2021 that could reflect changes in the magnetized accretion flow or an external Faraday screen. The improved 2021 coverage also provides the first EHT constraints on jet emission outside the ring, on scales of ≲1 mas. Overall, these observations provide strong proof of the reliability of the EHT images and probe the dynamic properties of the horizon-scale accretion flow surrounding M87*.

Astronomy and AstrophysicsVol. 704
University of Lethbridge (CA), Canadian Institute for Advanced Research (CA), Boston University (US), King University (US), Hiroshima University (JP), Goethe University Frankfurt (DE), Tokyo Electron (Japan) (JP), Tokyo Institute of Technology (JP), Kogakuin University (JP), University of Hawaiʻi at Mānoa (US), University of Science and Technology (YE), Leiden University (NL), California Institute of Technology (US), Las Cumbres Observatory Global Telescope Network (US), Google (United States) (US), Centre National de la Recherche Scientifique (FR), Space Telescope Science Institute (US), Space Science Institute (US), Planetary Science Institute (US), Pontificia Universidad Católica de Valparaíso (CL), Georgia Institute of Technology (US), Royal Netherlands Meteorological Institute (NL), Consejo Nacional de Ciencia y Tecnología (GT), Institute of Astronomy and Astrophysics, Academia Sinica (TW), Fermi National Accelerator Laboratory (US), National Taiwan Normal University (TW), Harvard University (US), Joint Institute for Laboratory Astrophysics (US), University of Arizona (US), Seoul National University (KR), University of Trieste (IT), National Sun Yat-sen University (TW), Radboud University Nijmegen (NL), University of Waterloo (CA), University of Turku (FI), Korea Advanced Institute of Science and Technology (KR), University of Illinois Urbana-Champaign (US), Kavli Institute for the Physics and Mathematics of the Universe (JP), National Taiwan University (TW), University of New Mexico (US), University of Cagliari (IT), University of Concepción (CL), University of Southern Denmark (DK), Universidade de São Paulo (BR), Shanghai Jiao Tong University (CN), Turku Centre for Computer Science (FI), Perimeter Institute (CA), University of Toronto (CA), Joint Institute for Nuclear Astrophysics (US), University of the Witwatersrand (ZA), Yonsei University (KR), Chinese Academy of Sciences (CN), The Graduate University for Advanced Studies, SOKENDAI (JP), Princeton University (US), Tohoku University (JP), Peking University (CN), Trinity College (CA), Université Paris Cité (FR), Cornell University (US), Academy of Athens (GR), Heidelberg University (DE), University of Würzburg (DE), National Radio Astronomy Observatory (US), Université Paris Sciences et Lettres (FR), Shanghai Astronomical Observatory (CN), Observatoire de Paris (FR), Czech Academy of Sciences, Astronomical Institute (CZ), Korea Astronomy and Space Science Institute (KR), Dutch Research Council (NL), Yunnan Observatories (CN), Frankfurt Institute for Advanced Studies (DE), Radboud University Medical Center (NL), Kyungpook National University (KR), Yale University (US), University of Malaya (MY), Nagoya City University (JP), Kyung Hee University (KR), Sorbonne Université (FR), University of Chicago (US), Central China Normal University (CN), Kavli Institute for Particle Astrophysics and Cosmology (US), National Institute of Technology, Ichinoseki College (JP), Institut de Radioastronomie Millimétrique (FR), Gemini North Observatory (US), Galaxies, Etoiles, Physique et Instrumentation (FR), Max Planck Institute for Astrophysics (DE), Istituto Nazionale di Fisica Nucleare, Sezione di Napoli (IT), Radboud Institute for Molecular Life Sciences (NL), Canadian Institute for Theoretical Astrophysics (CA), Delta Institute for Theoretical Physics (NL), Istituto di Radioastronomia di Bologna (IT), Inception Institute of Artificial Intelligence (AE), East Asian Observatory (US), Centre of Plasma Physics - Institute for Plasma Research (IN), Hachinohe National College of Technology (JP), Laboratoire d’études spatiales et d’instrumentation en astrophysique (FR), Gemini South Observatory (CL), Center for Astrophysics Harvard & Smithsonian (US), Northeast Radio Observatory Corporation (US), Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari (IT), Applied Mathematics (United States) (US), Astro-Med (United States) (US), The Institute of Statistical Mathematics (JP), National Center for Supercomputing Applications (US), Astronomical Institute of the Slovak Academy of Sciences (SK), Astronomy and Space (AU), Osservatorio Astronomico di Cagliari (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Trieste (IT), Foundation for Common Land (GB), Instituto de Geofísica y Astronomía (CU), Astronomical Observatory (RS), Laboratório Nacional de Astrofísica (BR), Max Planck Institute for Radio Astronomy (DE), Instituto de Astrofísica de Andalucía (ES), National Astronomical Observatory of Japan (JP), National Astronomical Observatories (CN), Applied Materials (Germany) (DE), Imaging Center (US), University of Wisconsin–Milwaukee (US), University College London (GB), The University of Texas at San Antonio (US), Huazhong University of Science and Technology (CN), Ulsan National Institute of Science and Technology (KR), McGill University (CA), Universitat de les Illes Balears (ES), Inter-University Centre for Astronomy and Astrophysics (IN), Massachusetts Institute of Technology (US), Chalmers University of Technology (SE), University of Maryland, College Park (US), Brandeis University (US), University of Pretoria (ZA), University of Naples Federico II (IT), Niigata University (JP), Rice University (US), The University of Tokyo (JP), Villanova University (US), Joint Institute for VLBI ERIC (NL), Heidelberg University (US), Michigan State University (US), Nanjing University (CN), University of Amsterdam (NL), Universidad Nacional Autónoma de México (MX), Netherlands Institute for Radio Astronomy (NL), Aalto University (FI)
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