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An animated look at black-hole spin

See what astronomers are talking about with these animations of black holes.
Scientists' newfound ability to peer near a black hole's event horizon has profound implications. In a few decades, when astronomers have measured the spins of many black holes, they'll be able to put general relativity to the test as never before. Will Einstein's theory, now more than a century old, survive the most intense tests we can imagine? Will he still have the last word on gravity?

More practically, astronomers want to know how stellar and supermassive black holes are able to launch relativistic jets of matter and align them over long distances. Long-duration gamma-ray bursts are thought to occur when the core of a massive star collapses into a black hole. As more of the star falls onto the hole, an accretion disk forms and, somehow, launches a relativistic jet up the star's spin axis. The result, most of the time, appears to be a gamma-ray burst followed by an underlying supernova.

But what energy source launches the jet? Processes in the accretion disk itself? Or amplified magnetic fields that tap into a black hole's enormous rotational energy? Astronomers can't yet answer these questions.
Cygnus X-1
Gas from a blue-giant star streams toward the black hole in a binary system modeled after Cygnus X-1. The gas orbits the black hole and forms an accretion disk. Gas orbiting closer to the black hole moves faster than gas farther out. The interaction of material moving at different speeds heats the gas to millions of degrees — hot enough to emit X rays. The gap between the gas disk and the black hole, seen near the video's end, represents the innermost orbit matter can take before plunging into the black hole.
Downloadable File(s)
Black-hole comparison
This video illustrates the difference between spinning and non-spinning black holes. Lines of space-time radiate from the event horizon, which is surrounded by a deep blue glow representing gas about to fall in. The innermost stable orbit is the lighter blue gas ring outside the event horizon. Note the curving lines of space-time around the rotating black hole, caused by the spinning hole dragging space-time along with it. As a result, the gas can orbit closer to the event horizon.
Downloadable File(s)
Black-hole comparison
The faster a black hole spins, the closer infalling gas can get. Because gravity is stronger closer to the black hole, light becomes more stretched there. So, a spinning black hole has a "broader" spectrum — one that has been stretched to lower energies.
Downloadable File(s)
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