A supermassive black hole lurking at the center of M87, a supergiant galaxy 55 million light-years from Earth, is acting far more strangely than anticipated.
Since 2017, astronomers from the Event Horizon Telescope (EHT) — an international collaboration combining a global network of radio telescopes — have closely watched the enormous gaping maw, resulting in the first-ever images of a black hole ever captured by humankind.
Now, by comparing observations from 2017, 2018, and 2021, scientists made a surprising discovery about how the magnetic fields near the black hole, dubbed M87*, change over time.
As detailed in a new paper published in the journal Astronomy & Astrophysics, an international team of astronomers discovered that the black hole's polarization flipped between 2017 and 2021, raising the possibility of a complex internal magnetic structure near its event horizon, the boundary in space beyond which nothing, even including light, can escape.
The findings suggest that magnetic fields play a significant role in how matter gets sucked up into the black hole and how energy gets spat back out, while also highlighting how much there's still to learn about these cosmic monstrosities.
"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 coauthor and Harvard astronomer Paul Tiede in a statement. "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."
Thanks to many improvements and instrument upgrades to the EHT project, scientists now have a smorgasbord of new data to examine that "will certainly keep us busy for many more years," co-lead and Radboud University Nijmegen assistant professor Michael Janssen added.
According to the analysis, M87*'s polarization pattern flipped between 2017 and 2021, which "was totally unexpected," as coauthor and Kyunghee University astronomer Jongho Park put it in the statement.
The finding "challenges our models and shows there’s much we still don’t understand near the event horizon," he added.
Thanks to several new telescopes that were added to the EHT's global network in 2021, the team was able to examine the spiraling, jet-like beams of energetic particles leaving M87* at almost the speed of light.
This enhanced sensitivity allowed them to detect "subtle polarization signals," as coauthor and Max Planck Institute for Radio Astronomy postdoctoral researcher Sebastiano von Fellenberg explained in the statement.
The scientific community is celebrating the latest findings as a major breakthrough in our understanding of black holes.
"These results show how the EHT is evolving into a fully fledged scientific observatory, capable not only of delivering unprecedented images, but of building a progressive and coherent understanding of black hole physics," said University of Naples Federico II astronomy professor and EHT project scientist Mariafelicia De Laurentis.
"It is a concrete demonstration of the extraordinary scientific potential of this instrument," she added.
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