Columbia researchers predict that a pair of converging supermassive black holes in the Virgo constellation will collide sooner than expected. Above, an artist’s conception of a merger. CREDIT (P. Marenfeld/NOAO/AURA/NSF)
Astronomers have provided additional evidence that a pair of closely orbiting black holes deep in the Virgo constellation is causing the rhythmic flashes of light coming from quasar PG 1302-102. Based on calculations of the pair’s mass – together, and relative to each other – the researchers go on to predict a smashup 100,000 years from now, far sooner than previously predicted. The collision will be so powerful it would send a burst of gravitational waves surging through the fabric of space-time itself.
Spiraling together 3.5 B light-years away, in Virgo constellation, the pair is separated by a mere light-week. By contrast, the closest previously confirmed black hole pair is separated by 20 light-years. “This is the closest we’ve come to observing two black holes on their way to a massive collision,” said Zoltan Haiman,. “Watching this process reach its culmination can tell us whether black holes and galaxies grow at the same rate, and ultimately test a fundamental property of space-time: its ability to carry vibrations called gravitational waves, produced in the last, most violent, stage of the merger.”
A supermassive black hole about to cannibalize its own can be detected by the mysterious flickering of a quasar – the beacon of light produced by black holes as they burn through gas and dust swirling around them. Normally, quasars brighten and dim randomly, but when 2 black holes are on the verge of uniting, the quasar appears to flicker at regular intervals.
A black hole merger is expected to release the gravitational waves predicted by Einstein, but not yet detected. Above, an artist’s conception of waves rippling through space-time. Credit: NASA
Recently, a team led by Matthew Graham, a computational astronomer at the California Institute of Technology, designed an algorithm to pick out repeating light signals from 247,000 quasars monitored by telescopes in Arizona and Australia. Of the 20 pairs of black hole candidates discovered, they focused on the most compelling bright quasar– PG 1302-102 which appeared to brighten by 14% every 5 years, indicating the pair was less than 1/10 of a light-year apart.
Haiman built a model to explain the repeating signal. By estimating the combined and relative mass of PG 1302-102’s black holes, they narrow down the pair’s predicted crash time to between 20,000 and 350,000 years from now with a best estimate of 100,000 years.
“We can start to put numbers on the rates that black holes come together and build up into larger black holes, and use what we’re learning to search for more black holes pairs,” said study coauthor David Schiminovich, an astronomer at Columbia. Also “The detection of gravitational waves lets us probe the secrets of gravity and test Einstein’s theory in the most extreme environment in our universe–black holes.” http://www.eurekalert.org/pub_releases/2015-09/cu-nsf090915.php
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