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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 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 6 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."