Newspaper article International New York Times

Analysis Supports Black Hole Collision ; Evidence Points to Doom for a Galaxy 3.5 Billion Light-Years from Earth

Newspaper article International New York Times

Analysis Supports Black Hole Collision ; Evidence Points to Doom for a Galaxy 3.5 Billion Light-Years from Earth

Article excerpt

A new report supports the theory that two black holes in a galaxy 3.5 billion light-years away are headed for a cosmic collision of unimaginable scale.

The apocalypse is still on, apparently -- at least in a galaxy about 3.5 billion light-years from here.

Last winter a team of astronomers at the California Institute of Technology reported that a pair of supermassive black holes appeared to be spiraling together toward a cataclysmic collision that could bring down the curtains in that galaxy.

The evidence was a rhythmic flickering from the galaxy's nucleus, a quasar known as PG 1302-102, which Matthew Graham and his colleagues interpreted as the fatal mating dance of a pair of black holes with a total mass of more than a billion suns. Their merger, the astronomers calculated, could release as much energy as 100 million supernova explosions, mostly in the form of violent ripples in space-time known as gravitational waves that would blow the stars out of that hapless galaxy as leaves off a roof.

Now a new analysis of the system by Daniel D'Orazio of Columbia University and his colleagues has added weight to that conclusion. Mr. D'Orazio, a graduate student, and his colleagues Zoltan Haiman and David Schiminovich propose that most of the light from the quasar is coming from a vast disk of gas surrounding the smaller of the two black holes.

As the black holes and their attendant disks swing around each other at high speeds, the light from the disk that is coming toward us gets amplified from relativistic effects -- a so-called Doppler boost -- the same way a siren gets louder and more high-pitched as it approaches, giving rise to a periodic increase in brightness every five years.

The model by the Columbia astronomers predicts that the variation would be two or three times greater in ultraviolet light than in visible light. And that is exactly what they found when they compared archival data from the Hubble Space Telescope and NASA's Galex space telescope with the visible-light data previously analyzed by Dr. Graham's group.

"What's big is that the Doppler boost is inevitable," Dr. Haiman said in an email. Given reasonable assumptions about the masses of the two black holes, their model predicts the right ultraviolet data. "This is rare in 'messy' astronomy," he said, "to have an indisputable clean effect, which explains the data."

Follow-up observations of ultraviolet and visible light emissions in the coming years could help the clinch the case, the authors said. Their paper was published on Wednesday in the journal Nature.

Their model suggests that the black holes are orbiting each other at a distance of some 200 billion miles, less than a tenth of a light-year, a cosmic whisker. …

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