Editor's note: This story will be updated throughout the day as more information becomes available.
This is what a black hole looks like.
A world-spanning network of telescopes called the Event Horizon Telescope zoomed in on the supermassive monster in the galaxy M87 to create this first-ever picture of a black hole.
“We have seen what we thought was unseeable. We have seen and taken a picture of a black hole,” Sheperd Doeleman, EHT Director and astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., said April 10 in Washington, D.C., at one of seven concurrent news conferences. The results were also published in six papers in the Astrophysical Journal Letters.
“Weve been studying black holes so long, sometimes its easy to forget that none of us have actually seen one,” France Cordova, director of the National Science Foundation, said in the Washington, D.C., news conference. Seeing one “is a Herculean task,” she said.
That's because black holes are notoriously hard to see. Their gravity is so extreme that nothing, not even light, can escape across the boundary at a black hole's edge, known as the event horizon. But some black holes, especially supermassive ones dwelling in galaxies centers, stand out by voraciously accreting bright disks of gas and other material. The EHT image reveals the shadow of M87s black hole on its accretion disk. Appearing as a fuzzy, asymmetrical ring, it unveils for the first time a dark abyss of one of the universes most mysterious objects.
“Its been such a buildup,” Doeleman said. “It was just astonishment and wonder… to know that youve uncovered a part of the universe that was off limits to us.”
The image aligns with expectations of what a black hole should look like based on Einsteins general theory of relativity, which predicts how spacetime is warped by the extreme mass of a black hole. The picture is “one more strong piece of evidence supporting the existence of black holes. And that, of course, helps verify general relativity,” says physicist Clifford Will of the University of Florida in Gainesville who is not on the EHT team. “Being able to actually see this shadow and to detect it is a tremendous first step.”
Earlier studies have tested general relativity by looking at the motions of stars (SN: 8/18/18, p. 12) or gas clouds (SN: 11/24/18, p. 16) near a black hole, but never at its edge. “Its as good as it gets,” Will says. Tiptoe any closer and youd be inside the black hole — unable to report back on the results of any experiments.
“Black hole environments are a likely place where general relativity would break down,” says EHT team member Feryal Özel, an astrophysicist at the University of Arizona in Tucson. So testing general relativity in such extreme conditions could reveal deviations from Einsteins predictions.
Just because this first image upholds general relativity "doesnt mean general relativity is completely fine,” she says. Many physicists think that general relativity wont be the last word on gravity because its incompatible with another essential physics theory, quantum mechanics, which describes physics on very small scales.
The image also provides a new measurement of the black holes size and heft. “Our mass determination by just directly looking at the shadow has helped resolve a longstanding controversy,” Sera Markoff, a theoretical astrophysicist at the University of Amsterdam, said in the Washington, D.C., news conference. Estimates made using different techniques have ranged between 3.5 billion and 7.22 billion times the mass of the sun. But new the EHT measurements show that its mass is about 6.5 billion solar masses.
The team has also determined the behemoths size — its diameter stretches 38 billion kilometers — and that the black hole spins clockwise. “M87 is a monster even by supermassive black hole standards,” Sera said.
EHT trained its sights on both M87s black hole and Sagittarius A*, the supermassive black hole at the center of the Milky Way. But, it turns out, it was easier to image M87s monster. That black hole is 55 million light-years from Earth in the constellation Virgo, about 2,000 times as far as Sgr A*. But its also about 1,000 times as massive as the Milky Ways giant, which weighs the equivalent of roughly 4 million suns. That extra heft nearly balances out M87s distance. “The size in the sky is pretty darn similar,” says EHT team member Feryal Özel.
Due to its gravitational oomph, gases swirling around M87s black hole move and vary in brightness more slowly than they do around the Milky Ways. “During a single observation, Sgr A* doesnt sit still, whereas M87 does,” says Özel, an astrophysicist at the University of Arizona in Tucson. “Just based on this Does the black hole sit stilRead More – Source
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