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• New event-horizon-telescope (EHT) images of M87* reveal unexpected flips in polarized light between 2017 and 2021, showing that magnetic fields near the black hole are dynamic and evolving.
• For the first time, the EHT detects faint jet emission near the base of M87’s relativistic jet, enabled by added telescopes and improved calibration.
• These findings confirm Einstein’s predictions of a stable black hole shadow while uncovering surprising turbulence in magnetic fields and jet formation.
The Event Horizon Telescope (EHT) collaboration, with a substantial contribution from the Max Planck Institute for Radio Astronomy (MPIfR), has unveiled new, detailed images of the supermassive black hole at the center of the galaxy M87. These reveal a dynamic environment with changing polarization patterns near the black hole. For the first time in EHT data, scientists have also detected signatures of extended jet emission near the jet base, where it connects to the ring around the black hole. These new observations, published today in Astronomy & Astrophysics, offer fresh insight into how matter and energy behave in the extreme environments surrounding black holes.
Located about 55 million light-years from Earth, M87 harbors a supermassive black hole more than six billion times the mass of the Sun. The EHT—a global network of radio telescopes acting as an Earth-sized observatory—first captured the iconic image of M87’s black hole shadow in 2019, adding polarization maps in 2021. In astronomy, polarization refers to the orientation of light waves, which can reveal the structure and strength of magnetic fields in space. Now, by comparing observations from 2017, 2018, and 2021, scientists have taken the next step toward uncovering how the magnetic fields near the black hole change over time.
Changing Polarization Pattern of M87*
Between 2017 and 2021, the polarization pattern unexpectedly flipped direction. In 2017, the magnetic fields appeared to spiral one way; by 2018, they had stabilized, and in 2021, they reversed, spiraling the opposite way. Such changes may result from both the black hole’s own magnetic structure and intervening matter that twists the light’s polarization on its journey to Earth. Together, these variations point to an evolving, turbulent environment in which magnetic fields play a crucial role in directing how matter falls into the black hole and how energy is directed into the jet moving outward. This surprising behavior challenges existing models and underscores how much remains to be understood about processes near the event horizon.
“What’s remarkable is that while the ring size has remained consistent over the years—confirming the black hole’s shadow predicted by Einstein’s theory—the polarization pattern changes significantly,” says Paul Tiede, an astronomer at the Center for Astrophysics | Harvard & Smithsonian, and a co-lead of the new study. “This tells us that the magnetized plasma swirling near the event horizon is far from static; it’s dynamic and complex, pushing our theoretical models to the limit.”
“Year after year, we improve the EHT – with additional telescopes and upgraded instrumentation, new ideas for scientific explorations, and novel algorithms to get more out of the data,” adds co-lead Michael Janssen, an assistant professor at the Radboud University Nijmegen, also affiliated to the MPIfR. “For this study, all these factors nicely conspired into new scientific results and new questions, which will certainly keep us busy for many more years.”
“Jets like the one in M87 play a key role in shaping the evolution of their host galaxies. By regulating star formation and distributing energy across vast distances, they affect the life cycle of matter on cosmic scales,” explains Eduardo Ros from MPIfR. “Since M87’s jet emits across the entire spectrum—from radio waves to gamma rays and neutrinos—it provides a unique laboratory for investigating how such extreme cosmic phenomena form and are launched.”
Two New Telescopes in the EHT Network
Crucially, the 2021 EHT observations included two new telescopes—Kitt Peak in Arizona and NOEMA in France—which enhanced the array’s sensitivity and image clarity. This allowed scientists to constrain, for the first time with the EHT, the emission direction of the base of M87’s relativistic jet—a narrow beam of energetic particles blasting out from the black hole at nearly the speed of light. Technical performance upgrades at the Greenland Telescope and James Clerk Maxwell Telescope have further improved the data quality in 2021.
“The improved calibration has led to a remarkable boost in data quality and array performance, with new short baselines—between NOEMA and the IRAM 30m telescopes, and between Kitt Peak and SMT, providing the first constraints on the faint jet base emission,” says Sebastiano von Fellenberg, formerly at MPIfR, and now Humboldt-Lynen Fellow at CITA (University of Toronto), who focused on the calibration for the project. “This leap in sensitivity also enhances our ability to detect subtle polarization signals.”
Thomas Krichbaum from MPIfR comments: “These multi-year observations reveal just how turbulent and dynamic the environment is close to the event horizon. The next step will be to capture the variations of ring and jet with more frequent observations, ideally in a movie which would address the still poorly understood kinematics on event horizon scales.”
These multi-year images deepen our understanding of one of the Universe’s most extreme environments. They confirm Einstein’s predictions while uncovering new complexities in magnetic fields and jet formation, offering an unprecedented view of the black hole’s immediate surroundings.
J. Anton Zensus, founding chair of the EHT collaboration and director at MPIfR, concludes: “These latest results illustrate the remarkable dynamism around a supermassive black hole. The evolving polarization patterns and the first insights into the jet base bring us closer to understanding the interplay between magnetic fields, accretion, and jet launching. They also demonstrate the value of long-term international collaboration and sustained technical innovation in radio astronomy, opening entirely new windows onto the Universe.”
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Additional Information
The EHT collaboration involves more than 400 researchers from Africa, Asia, Europe, North and South America, with around 270 participating in this paper. The international collaboration aims to capture the most detailed images of black holes using a virtual Earth-sized telescope. Supported by considerable international efforts, the EHT links existing telescopes using novel techniques to create a fundamentally new instrument with the highest angular resolving power that has yet been achieved.
The EHT consortium consists of 13 stakeholder institutes; the Academia Sinica Institute of Astronomy and Astrophysics, the University of Arizona, the Center for Astrophysics | Harvard & Smithsonian, the University of Chicago, the East Asian Observatory, the Goethe University Frankfurt, the Institut de Radioastronomie Millimétrique, the Large Millimeter Telescope, the Max Planck Institute for Radio Astronomy, the MIT Haystack Observatory, the National Astronomical Observatory of Japan, the Perimeter Institute for Theoretical Physics, and the Radboud University.
The EHT array operating at 1.3 mm wavelength included ALMA, APEX, the IRAM 30-meter Telescope, the IRAM NOEMA Observatory, the James Clerk Maxwell Telescope (JCMT), the Large Millimeter Telescope (LMT), the Submillimeter Array (SMA), the Submillimeter Telescope (SMT), the South Pole Telescope (SPT), the Kitt Peak Telescope (KP), and the Greenland Telescope (GLT). EHT data were post-processed at the MPIfR correlator facility as well as at the MIT/Haystack Observatory in Westford, MA, USA.
Following forty individuals affiliated to the MPIfR are coauthors in this publication: Walter Alef, Rebecca Azulay, Uwe Bach, Anne-Kathrin Baczko, Silke Britzen, Gregory Desvignes, Sergio A. Dzib, Ralph P. Eatough, Sebastiano D. von Fellenberg, Christian M. Fromm, Michael Janssen, Ramesh Karuppusamy, Joana A. Kramer, Michael Kramer, Thomas P. Krichbaum, Jun Liu, Andrei P. Lobanov, Ru-Sen Lu, Nicholas R. MacDonald, Nicola Marchili, Karl M. Menten, Cornelia Müller, Hendrik Müller, Dhanya G. Nair, Georgios Filippos Paraschos, Alexander Plavin, Eduardo Ros, Helge Rottmann, Alan L. Roy, Saurabh, Tuomas Savolainen, Lijing Shao, Pablo Torne, Efthalia Traianou, Jan Wagner, Robert Wharton, Gunther Witzel, Jompoj Wongphexhauxsorn, J. Anton Zensus, and Guang-Yao Zhao. 
This research received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreements RadioNet (No 730562) and M2FINDERS (No 101018682), as well as funding from the European Research Council (ERC) under the Seventh Framework Programme via the Synergy Grant “BlackHoleCam: Imaging the Event Horizon of Black Holes” (Grant No 610058).
Dr. Sebastiano von Fellenberg
Max Planck Institute for Radio Astronomy, Bonn
& Canadian Institute for Theoretical Astrophysics (CITA) at the University of Toronto
Fon: +1 437 328 5547
sfellenberg@mpifr-bonn.mpg.de
Dr. Michael Janssen
Radboud University, Nijmegen, The Netherlands
& Max Planck Institute for Radio Astronomy, Bonn
michael.janssen@ru.nl
Dr. Thomas Krichbaum
Max Planck Institute for Radio Astronomy, Bonn
Fon: +49 228 525-295
tkrichbaum@mpifr-bonn.mpg.de
Prof. Dr. Eduardo Ros
Max Planck Institute for Radio Astronomy, Bonn
Fon: +49 228 525-125
ros@mpifr-bonn.mpg.de
“Horizon-scale variability of from 2017--2021 EHT observations”, EHT Collaboration et al., Astronomy & Astrophysics Vol. 701, 16 September 2025
https://doi.org/10.1051/0004-6361/202555855
https://www.mpifr-bonn.mpg.de/pressreleases/2025/6
New images from the Event Horizon Telescope (EHT) collaboration have revealed a dynamic environment ...
Copyright: EHT Collaboration
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