AUSTIN, Texas — The most massive black hole inthe universe tips the cosmic scales at 18 billion times more massive than thesun, astronomers suggest today at a meeting of the American AstronomicalSociety.
Even thoughresearchers suggested black holesup to this mass might exist in quasars, this is the first direct confirmationof such a behemoth.
The heftygravity well is six times more massive than the previous record and is orbitedby a smallerblack hole, which allowed the measurement of the giant's mass.
Black holescan't be seen, but astronomers detect them by noting how other objects are affectedby the tremendous gravity created in tremendously small sphere of space.
The binaryblack hole system powers a quasar known as OJ287, which is located 3.5 billionlight-years from us in the constellation Cancer. The quasar — an overwhelmingbeacon of light associated with a developing galaxy — has been studied ingreater detail than most quasars.
Quasars arethought to be powered by gas falling into giant black holes boasting millionsor billions of solar masses. Though smaller than the solar system, aquasar can outshine an entire galaxy.
Thisparticular quasar has a regularly pulsing light signal with two major pulsesevery 12 years. The first two pulses were observed in the year 1994-1995, andthe first one of the next set in 2005. The observations helped astronomersrefine their computer models, predicting the next pulse would come on Sept. 13,2007.
MauriValtonen of the Tuorla Observatory in Finland, who presented the study, saysthere is a simple physical explanation for the 12-year pulsing. "Inaddition to the primary back hole in the[accretion] disk, we have a secondary black hole that crosses the disktwice during the orbital period," Valtonen said. "And that's whatgives us the two pulses."
Aninternational network of astronomers operating telescopes across the globe tookpart in monitoring the quasar in September and October. The largest telescopesinvolved were the German Calar Alto telescope and the Nordic optical telescope.
Sureenough, right on schedule OJ287 sent out a light pulse on that date. No otherpulses of that kind showed up during September or October, indicating, theastronomers say, the binary black-hole model was correct.
The nextpulse is due in January 2016.
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