Images taken of the Universe’s most photogenic black hole over time reveal strange and exciting changes in its magnetic field.
Using observations obtained using the Event Horizon Telescope in 2017, 2018, and 2021, scientists mapped changes in the polarization of M87*’s magnetic field, suggesting that, while the black hole itself is stable, there’s wild and dynamic cosmic weather raging outside its event horizon.
In fact, between 2017 and 2021, the magnetic field completely flipped direction – the first time such a change has been seen in the environment around a black hole. The results could help us understand how these cosmic behemoths feed, and what powers the extreme jets they launch out into intergalactic space.
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M87* is a supermassive black hole in a galaxy 55 million light-years away with a mass around 6.5 billion times the mass of the Sun. As the first subject of the Event Horizon collaboration’s mission to image a supermassive black hole, the object has become one of the most studied supermassive black holes in the entire Universe.
Since the first iconic image was released in 2019, the collaboration has continued to observe M87*, collecting data across the years to track any changes in the mass of hot material roiling around the black hole’s edge. That includes the best observations to date of the place where jets are launched from the poles of an active black hole.
“Jets like the one in M87 play a key role in shaping the evolution of their host galaxies,” explains astronomer Eduardo Ros of the Max Planck Institute for Radioastronomy in Germany. “By regulating star formation and distributing energy across vast distances, they affect the life cycle of matter on cosmic scales.”
A black hole’s magnetic field is thought to play a key role in creating its jets. As material swirls near a black hole, it arranges itself into a disk around the equator. However, not all the material from the disk’s inner rim ends up crossing into oblivion, to never be seen again.
Some, according to theory, is diverted along the magnetic field lines that surround the black hole’s event horizon. It’s accelerated to the poles, from where it is launched into space at insanely high speeds, approaching that of light in a vacuum. These jets punch out through space for up to millions of light-years.
To help understand how these jets can form in the crazy environment close to a black hole, the Event Horizon Telescope collaboration took a series of images of M87* across multiple years and studied them closely to map the changes in the material around the black hole.
The polarization of the light was a particular focus. When light travels through a strongly magnetized environment, the orientation of its waves can become organized and aligned. Although the images of M87* don’t seem to change much over time, once the polarization data is overlaid, quite dramatic variations appear.
In 2017, the magnetic fields appeared to spiral clockwise. By 2018, they shifted anti-clockwise and appeared to stabilize. By 2021, they appeared to spiral in an anti-clockwise direction. These results suggest that the magnetic fields around M87* change significantly, and on very short cosmic timescales, while the black hole itself remains the same.
frameborder=”0″ allow=”accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share” referrerpolicy=”strict-origin-when-cross-origin” allowfullscreen>“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 astronomer Paul Tiede of the Harvard & Smithsonian Center for Astrophysics.
“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 new results reveal a dynamic, turbulent, ever-changing environment, showing how a supermassive black hole’s wild magnetic fields help direct the flow of material – some beyond the event horizon, and some hurled out into space in the form of giant jets.
Future observations will build on these findings, offering more profound insight into M87*’s fascinating magnetic environment.
“Pioneering a new frontier in time-domain black hole astrophysics, the Event Horizon Telescope is planning an ambitious series of rapid-fire observations across March and April 2026,” says astronomer Remo Tilanus of The University of Arizona’s Steward Observatory.
“We are excited to be gearing up to capture the first movie of M87*, something that has been on our wish list ever since that first image of a black hole.”
The research has been published in Astronomy & Astrophysics.