Catch a Wave - Laser Interferometer Gravitational-Wave Observatory research

Science News,  Jan 8, 2000  by Peter Weiss

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At its planned sensitivity, LIGO may detect a handful of black hole mergers--the events it has the best chance of catching--during its first 3-year scientific run, its designers say. On the other hand, if it makes no detection during its inaugural period, they won't be dismayed.

"Our plan has always been to turn it on at a sensitivity where it is likely to see something and then upgrade to where it would be surprising if it does not," says Thorne, who was one of the original proponents of LIGO in the 1960s.

Researchers are already working on the improved technology to be installed in 2005. At that time, LIGO is scheduled to switch, for instance, from quartz mirrors to synthetic sapphire ones, which are denser and shed the laser beam's heat more efficiently.

The overhaul should boost the observatory's sensitivity approximately 15-fold, Thorne says, increasing its detection range for a black hole merger from 600 million light-years away to nearly 10 billion light-years. By eavesdropping on so much more space, LIGO should raise its rate of detecting sources by a factor of more than 3,000.

Looking beyond even the upgraded LIGO, space agency officials in the United States and Europe are considering building an orbiting gravitational wave observatory called the Laser Interferometer Space Antenna, or LISA. It would extend gravitational wave observations into a much lower frequency range--from a cycle every 10 seconds to one every 3 hours. Scientists could then tune in to slowly orbiting binary stars and colliding galaxies with huge black holes at their cores.

Consisting of three spacecraft in a triangular array, 5 million km on a side, LISA is "the wave of the future for this field," says Weiss, who 30 years ago came up with the concept of using interferometers for gravitational wave detection. Because signals in LISA's band are expected to be stronger and more abundant than those that would trigger ground-based detectors, the space observatory would be able to detect several sources every week, he says.

Maybe then gravitational waves will seem as commonplace as scientists say they really are.

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