New EHT Images Reveal Black Hole’s Magnetic Field Flips Direction
Multi-year Event Horizon Telescope observations capture evolving polarization patterns in supermassive black hole and see emissions in 230 GHz near the base of its jet
New images from the Event Horizon Telescope (EHT) collaboration have revealed a dynamic environment with changing polarization patterns in the magnetic fields of supermassive black hole M87*. As shown in the images above, while M87*’s magnetic fields appeared to spiral one direction in 2017, they settled in 2018 and reversed direction in 2021. The cumulative effects of this polarization change over time suggests that M87* and its surrounding environment are constantly evolving. Credit: EHT Collaboration
The Event Horizon Telescope (EHT) collaboration has unveiled new, detailed images of the supermassive black hole at the center of the galaxy M87, revealing a dynamic environment with changing polarization patterns near the black hole. Additionally, the scientists found the first signatures of the extended jet emission near the jet base, which connects to the ring around the black hole, in EHT data. These new observations, published today in Astronomy & Astrophysics are providing new insight into how matter and energy behave in the extreme environments surrounding black holes.
Dr. Sebastiano von Fellenberg, a postdoctoral researcher at the Canadian Institute for Theoretical Astrophysics, Max Planck Institute for Radio Astronomy (MPIfR) and Humboldt Feodor Lynen Fellow is a key contributor to this latest EHT publication. Leading the calibration of the new 2021 observations, he corrected for atmospheric interferences and slight differences between the telescopes.
Located about 55 million light-years away 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 in 2021. Now, by comparing observations from 2017, 2018, and 2021, scientists have taken the next step towards uncovering how the magnetic fields near the black hole change over time.
“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,” said 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.”
The most recent 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. Upgrades at the Greenland Telescope and James Clerk Maxwell Telescope have further improved the data quality in 2021.
“What is genuinely new here is that we can now place constraints on emission originating from the very base of the jet, rather than emission coming from the bright “ring” structure,” said Dr. von Fellenberg.
“This is exciting because it provides new information on how enormous, kiloparsec-scale jets are launched – one of the main outstanding questions in jet physics. With just two sensitive baselines, our current EHT observations cannot yet form a detailed image of this region. However, we can now detect its presence, and that’s a significant step forward. It leaves us eager to see what upcoming data will reveal.”
Between 2017 and 2021, the polarization pattern of M87 flipped direction. In 2017, the magnetic fields appeared to spiral one way; by 2018, they settled; and in 2021, they reversed, spiraling the opposite direction. Some of these apparent changes in the polarization’s rotational direction may be influenced by a combination of internal magnetic structure and external effects, such as a Faraday screen. The cumulative effects of how this polarization changes over time suggests an evolving, turbulent environment where magnetic fields play a vital role in governing how matter falls into the black hole and how energy is launched outward.
“The fact that the polarization pattern flipped direction from 2017 to 2021 was totally unexpected,” Jongho Park, an astronomer at Kyunghee University and a collaborator on the project. “It challenges our models and shows there’s much we still don’t understand near the event horizon.”
Jets like M87’s play a crucial role in galaxy evolution by regulating star formation and distributing energy on vast scales. Emitting across the electromagnetic spectrum—including gamma rays and neutrinos—M87’s powerful jet provides a unique laboratory to study how these cosmic phenomena form and are launched. This new detection offers a vital piece of the puzzle.
Other members of the EHT collaboration at the University of Toronto include CITA faculty members Ue-Li Pen and Bart Ripperda, postdoctoral fellows Gibwa Musoke and Rohan Dahale and Aviad Levis, Assistant Professor at the Computer Science Department. While not directly involved in this project, they are excited by the marked improvement in the quality of the data and look forward to the next generation of EHT observations with even higher angular resolution.
“Due to the time scales of M87 (it is really massive, so it takes months to years for changes in the accretion flow to occur), we really need to have multi-year observations,” affirms Bart Ripperda. “In essence, we need a long-time-scale video of the black hole. The black hole flares about every few years, when it gets brighter and emits at very high (gamma-ray) energies. Those flares come from near the horizon in some cases, so if we want to monitor what is happening close to the event horizon we need to capture those flares.”
As the Event Horizon Telescope collaboration continues to expand its observational capabilities, these new results illuminate the dynamic environment surrounding M87* and deepen scientists’ understanding of black hole physics.
A&A Paper DOI: https://www.aanda.org/10.1051/0004-6361/202555855
A high-resolution version of the M87 2017-2021 image can be found here . Read the official EHT press release.
Media Contacts:
Amy C. Oliver, FRAS
Public Affairs Officer
Center for Astrophysics | Harvard & Smithsonian
amy.oliver@cfa.harvard.edu
Lyuba Encheva, Communications and Events Coordinator
Canadian Institute for Theoretical Astrophysics, University of Toronto
communication@cita.utoronto.ca
Science Contacts:
Paul Tiede
Center for Astrophysics | Harvard & Smithsonian
paul.tiede@cfa.harvard.edu
Michael Janssen
Radboud University
michael.janssen@ru.nl
Sebastiano von Fellenberg
Postdoctoral Researcher
Max Planck Institute for Radio Astronomy (MPIfR); Canadian Institute for Theoretical Astrophysics (CITA)
sfellenberg@mpifr-bonn.mpg.de
Jongho Park
Kyung Hee University
jparkastro@khu.ac.kr
Mariafelicia De Laurentis
University of Naples
mariafelicia.delaurentis@unina.it