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 emission associated with the jet of energetic particles blasting out from the black hole at nearly the speed of light.
These new observations, published in the journal Astronomy & Astrophysics are providing new insight into how matter and energy behave in the extreme environments surrounding black holes.
Sebastiano von Fellenberg, a postdoctoral researcher at the Canadian Institute for Theoretical Astrophysics (CITA) in the Faculty of Arts & Science, 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 that comprise the EHT. Von Fellenberg is also with the Max Planck Institute for Radio Astronomy (MPIfR) and is a Humboldt Feodor Lynen Fellow.
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.
In 2021, the collaboration began observing polarization of the light from M87. Most of the light we experience around us is not polarized; i.e. the waves of light vibrate in random directions. Polarized light is light that vibrates in an aligned, non-random way due to passing through a magnetic field.
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. 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,” says 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,” he says. “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 — something astronomers did not expect. 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. 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.
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, an assistant professor in the Department of Computer Science. 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.
“M87 is really massive, so it takes months to years for changes in the accretion flow to occur. Due to this timescale, we really need to have multi-year observations,” says Ripperda.
“In essence, we need a long-time-scale video of the black hole,” he says. “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.
With files from the EHT collaboration.