By Peter Weiss
In deep space, black holes may sometimes swirl together and then collide, sending out staggering bursts of gravitational waves. Scientists are developing sophisticated new instruments to measure such never-before-detected waves–which would be ripples in space-time itself (SN: 1/8/00, p. 26: Available to subscribers at Catch a Wave.). In the meantime, they’re wondering whether some evidence for these magnificent events has been under their noses for years.
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As it turns out, such titanic encounters sometimes leave behind a kind of celestial graffiti, a new study suggests. Ever since 1978, when Ron D. Ekers of the Australia Telescope National Facility in Epping and his colleagues first found a vast X-shaped source of radio waves centered on galaxy NGC 326, a growing roster of such crisscross formations has puzzled observers. In the past 2 decades, radioastronomers have identified about a dozen such sources.