for National Geographic News
Two newfound black holes on the verge of crashing into each other could be creating "ripples" in the fabric of space-time, astronomers suggest.
The two supermassive black holes orbit each other about once a century, separated by just a third of a light-year—and they seem to be getting closer, a new study says.
Such systems should be relatively common, but so far they have proven elusive, said study co-author Todd Boroson of the National Optical Astronomy Observatory in Tucson, Arizona.
"We believe that galaxies grow primarily by merging with other galaxies," he explained.
"If you have a black hole in the center of each, you'd expect to find systems where you have two black holes that gradually merge."
If confirmed, scientists will likely want to study this system intensely to figure out why they haven't seen others like it.
The binary black holes also could provide a unique environment to test aspects of Einstein's theory of general relativity, astronomers note.
The theory predicts that compact, massive bodies—such as black holes orbiting one another—should produce ripples in space-time that move at the speed of light.
Boroson and colleague Tod Lauer spotted the newfound binary black holes by examining data on more than 17,000 quasars from the Sloan Digital Sky Survey, a major mapping project that has so far imaged more than a quarter of the cosmos.
Each quasar is thought to represent a supermassive black hole at the center of a distant galaxy. Quasars are extremely bright because matter gets superheated as it falls into a black hole, sending out huge amounts of energy.
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