Black holes are powerful, whirling maelstroms that can have a mass billions of times that of our sun. (Photo : Wikimedia Commons)
You've probably heard of them. Huge, violent areas of space where the gravity pull is so strong that even light can't escape. Black holes, one of nature's most enigmatic forces, have still eluded proper scientific analysis due to their violent and elusive nature. Even detecting one is difficult since they are literally invisible. Now, however, a team of scientists have measure the radius of a black hole for the first time ever.
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The MIT Haystack Observatory researchers trained their sights on a black hole in nearby galaxy M87 50-million light-years away from our Milky Way. In it, they were able to figure out the radius of a black hole more than six billion times the mass of our sun by observing the point of no return - the "event horizon."
"Once objects fall through the event horizon, they're lost forever," says lead author of the study published in Science Shep Doeleman, assistant director at the MIT Haystack Observatory and research associate at the Smithsonian Astrophysical Observatory. "It's an exit door from our universe. You walk through that door, you're not coming back."
The glow of the matter in the event horizon before they were sucked in helped scientists since according to Einstein's theory, the mass and spin of a black hole determine where the event horizon lies.
"We are now in a position to ask the question, 'Is Einstein right?'" Doeleman says. "We can identify features and signatures predicted by his theories, in this very strong gravitational field."
To measure the radius of the black hole, the researchers connected a series of dishes in Hawaii, Arizona, and California to create an incredibly powerful telescope dubbed the "Event Horizon Telescope" that is 2,000 times more powerful than the Hubble Space Telescope.
The black hole's accretion disk's innermost orbit was found to be 5.5 times the size of the event horizon.
The findings will also help scientists understand more about the vicious jets that black holes spit out.
"The basic nature of jets is still mysterious," said Christopher Reynolds, a professor of astronomy at the University of Maryland. "Many astrophysicists suspect that jets are powered by black hole spin ... but right now, these ideas are still entirely in the realm of theory. This measurement is the first step in putting these ideas on a firm observational basis."