NASAs description: Astronomers from the University of Maryland, College Park (UMCP) and NASAs Goddard Space Flight Center have uncovered rhythmic pulsations from a rare breed of black hole in archival data from NASAs Rossi X-ray Timing Explorer (RXTE) satellite. (…) M82 X-1 is the brightest X-ray source in Messier 82, a galaxy located about 12 million light-years away in the constellation Ursa Major. While astronomers have suspected the object of being a midsize, or intermediate-mass, black hole for at least a decade, estimates have varied from 20 to 1,000 solar masses, preventing a definitive classification. (…) As gas streams toward the black hole it piles up into a disk around it. Friction within the disk heats the gas to millions of degrees, which is hot enough to emit X-rays. Cyclical intensity variations in these X-rays reflect processes occurring within the disk. (…) When astronomers study X-ray fluctuations from many stellar-mass black holes, they see both slow and fast QPOs, but the fast ones often come in pairs with a specific 3:2 rhythmic relationship. For every three flashes from one member of the QPO pair, its partner flashes twice. The combined presence of slow QPOs and a faster pair in a 3:2 rhythm effectively sets a standard scale that gives scientists a powerful tool for establishing the masses of stellar black holes. (…) By analyzing six years of data, they located X-ray variations that reliably repeated about 3.3 and 5.1 times each second, just the 3:2 relationship they needed. This allowed them to calculate that M82 X-1 weighs about 400 solar masses -- the most accurate determination to date for this object and one that clearly places it in the category of intermediate-mass black holes. Credit: NASAs Goddard Space Flight Center (August 2014)
Posted on: Mon, 29 Sep 2014 23:50:07 +0000
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