preview.tinyurl.com/293esb -> space.newscientist.com/article/dn13166-biggest-black-hole-in-the-cosmos-discovered.html?feedId=online-news_rss20
The quasar OJ287 contains two black holes (this slightly dated illustration lists the larger black hole's mass as 17 billion Suns, though researchers now estimate it is 18 billion Suns).
Enlarge image The quasar OJ287 contains two black holes (this slightly dated illustration lists the larger black hole's mass as 17 billion Suns, though researchers now estimate it is 18 billion Suns).
Advertising The most massive known black hole in the universe has been discovered, weighing in with the mass of 18 billion Suns. Observing the orbit of a smaller black hole around this monster has allowed astronomers to test Einstein's theory of general relativity with stronger gravitational fields than ever before. The black hole is about six times as massive as the previous record holder and in fact weighs as much as a small galaxy. It lurks 35 billion light years away, and forms the heart of a quasar called OJ287. A quasar is an extremely bright object in which matter spiralling into a giant black hole emits copious amounts of radiation. But rather than hosting just a single colossal black hole, the quasar appears to harbour two a setup that has allowed astronomers to accurately 'weigh' the larger one. The smaller black hole, which weighs about 100 million Suns, orbits the larger one on an oval-shaped path every 12 years. It comes close enough to punch through the disc of matter surrounding the larger black hole twice each orbit, causing a pair of outbursts that make OJ287 suddenly brighten. General relativity predicts that the smaller hole's orbit itself should rotate, or precess, over time, so that the point at which it comes nearest its neighbour moves around in space an effect seen in Mercury's orbit around the Sun, albeit on a smaller scale. Bright outbursts In the case of OJ287, the tremendous gravitational field of the larger black hole causes the smaller black hole's orbit to precess at an incredible 39 each orbit. The precession changes where and when the smaller hole crashes through the disc surrounding its larger sibling. About a dozen of the resulting bright outbursts have been observed to date, and astronomers led by Mauri Valtonen of Tuorla Observatory in Finland have analysed them to measure the precession rate of the smaller hole's orbit. That, along with the period of the orbit, suggests the larger black hole weighs a record 18 billion Suns. A couple of other black holes have been estimated to be as massive, but their masses are less certain, says Valtonen. That's because the estimates were based on the speed of gas clouds around the black holes, and it is not clear whether the clouds are simply passing by the black holes or actually orbiting them. But Tod Strohmayer of NASA's Goddard Space Flight Center in Maryland, US, says he is not convinced that Valtonen's team has really measured the mass of the large black hole in OJ287 accurately. That's because only a handful of the outbursts have been measured with high precision, making it difficult to determine if the precession scenario is responsible for the outbursts. "Obviously, if subsequent timings continue to agree with the model, then that would provide further support," he told New Scientist. Craig Wheeler of the University of Texas in Austin, US, says it depends only on how long a black hole has been around and how fast it has swallowed matter in order to grow. The new research also tested another prediction of general relativity that the black holes should spiral towards each other as they radiate energy away in the form of gravitational waves, or ripples in space. This radiation affects the timing of the disc crossings and their accompanying outbursts. The most recent outburst occurred on 13 September 2007, as predicted by general relativity. "If there was no orbital decay, the outburst would have been 20 days later than when it actually happened," Valtonen told New Scientist, adding that the black holes are on track to merge within 10,000 years. Wheeler says the observations of the outbursts fit closely with the expectations from general relativity.
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By Andy S Thu Jan 10 12:08:55 GMT 2008 As I understand it (and forgive me, I'm no physicist), massive amounts of energy are released as matter falls into a black hole. With the smaller hole weighing an estimated 100 million tons - would this effectively be a cataclysmically large sterilisation event for and potential life across a very large swathe of the known universe?
By Stephen Baldwin Thu Jan 10 17:56:54 GMT 2008 The mass of the smaller black hole is 100 million suns not tons, and to my knolage the only energy to be reeased by black holes is Hawking evaporation due to 'virtual' particals at the event horizon. As these holes merge the entropy of the system will fall into yet larger entropy with all the chaos (infinite entropy) kept within.
VIEW THREAD >> Mass Not Weight By Ambika Thu Jan 10 12:25:18 GMT 2008 The smaller black hole, should have a MASS of about 100 million Suns, not WEIGHT as weight is dependant on the gravitational constant which changes with the gravitational environment around a body.
By Tony Thu Jan 10 12:51:13 GMT 2008 If the smaller black hole has an orbit of 12 years and causes an out burst twice per revoloution as it passes through the disc of matter surrounding the larger black hole. The text says "About a dozen of the resulting bright outbursts have been observed to date" that would take 72 years to observe meaning observation would have had to start in 1935, is that correct?
By Josh Thu Jan 10 23:09:22 GMT 2008 No, if it orbited every 12 years that would mean it would happen twice in on 12 year cycle, this would mean they would have been observing it for approx.
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