The popular notion of a black hole is as a space mouth, gobbling up anything and turning it into nothing. Scientists know that’s not actually how these phenomena work. Black holes often spew out jets of interstellar matter brighter than stars. But the mechanism by which a spinning black hole can generate these blasts of energy has always been a mystery.
Magnetic fields have been long thought to play a significant role, and new findings published Thursday in the journal Science seem to confirm this. Researchers at the Harvard-Smithsonian Center for Astrophysics have just detected the presence of magnetic fields at the Milky Way galaxy’s central black hole, Sagittarius A-star.
“These magnetic fields have been predicted to exist, but no one has seen them before,” Shep Doeleman, a co-author of the study, said in a statement. “Our data puts decades of theoretical work on solid observational ground.”
The CfA team found the magnetic fields protruding just outside the event horizon of the black hole, thanks to the Event Horizon Telescope — a conglomerate of radio telescopes around the world that operate together to observe and identify features in outer space — like the size of the golf ball on the moon.
That’s critical, because a black hole is pretty much the most compact object that exists in the universe. Sir A weighs 4 million times more than our own Sun, but has an event horizon that’s smaller than Mercury’s orbit.
When the CfA team began observing Sgr A, they noticed a polarized light was emitted. They traced the source back to electrons spiraling around what have to be magnetic field lines, and a larger magnetic field structure.
This particular magnetic field is actually a dynamic mess. The black hole is surrounded by a ton of interstellar junk, causing the magnetic field to show up as disordered loops and whorls in certain spots. Other, more organized ares could be signs of where jets of matter and energy are being expelled. The study helps researchers get closer to answering a question that, as Doelerman puts it, has mystified astronomers for decades now: “Why are black holes so bright?”
Perhaps it’s time to start considering a name change.