Astronomers using the Event Horizon Telescope, a global network of radio telescopes that link together to function as one giant telescope the size of Earth, have reportedly detected magnetic fields on the edge of a black hole’s event horizon for the very first time.
According to Michael Johnson of the Harvard-Smithsonian Center for Astrophysics (CfA), lead author of a new paper detailing the findings published in the December 4 edition of Science, his team’s discovery is a game-changer when it comes to our understanding of black holes.
“Understanding these magnetic fields is critical. Nobody has been able to resolve magnetic fields near the event horizon until now,” Johnson explained in a statement. While black holes are often compared to massive vacuum cleaners, sucking up anything that ventures too close, they actually convert energy from that infalling matter into extremely intense radiation.
If a black hole is spinning, it’s capable of generating strong jets that are beamed over thousands of light years and can have an impact on entire galaxies. This phenomenon has long been thought to be powered by magnetic fields, but none had ever actually been detected—until now.
Research could explain what makes black holes so bright
Thanks to the EHT, Johnson and his fellow researchers were able to detect magnetic fields on the outskirts of the event horizon of Milky Way’s central black hole, Sgr A* (Sagittarius A-star). Sgr A* weighs nearly four million times more than the sun, but its event horizon is only eight million miles—even smaller than Mercury’s orbit.
Because of this, and due to the fact that the black hole is located 25,000 light-years away, its size corresponds to a minuscule 10 micro-arcseconds across. However, its intense gravity warps light and magnifies the event horizon, making it appear five-times larger and allowing the EHT to observe it at a wavelength of 1.3 millimeters and measure the polarization of its light.
That polarized light is emitted by electrons spiraling around magnetic field lines, the Harvard-led team said. As a result, the light traces the structure of Sgr A*’s magnetic field, revealing that it is spaghetti-like and jumbled in some areas and far more organized in others—possibly including the region from which jets would originate.
“These magnetic fields have been predicted to exist, but no one has seen them before. Our data puts decades of theoretical work on solid observational ground,” said Shep Doleman, assistant director of the MIT’s Haystack Observatory. “With this result, the EHT team is one step closer to solving a central paradox in astronomy: why are black holes so bright?”
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Feature Image: M. Weiss/CfA
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