This image, taken with the European Southern Observatory’s Very Large Telescope, shows the central region of galaxy NGC1313. This galaxy is home to the ultraluminous X-ray source NCG1313X-1, which astronomers have now determined to be an intermediate-mass black hole candidate. NGC1313 is 50,000 light-years across and lies about 14 million light-years from the Milky Way in the southern constellation Reticulum. Credit: ESO
Nearly all black holes come in 1 of 2 sizes: stellar mass black holes that weigh up to a few dozen times the mass of our sun or supermassive black holes ranging from a million to several billion times the sun’s mass. Astronomers believe that medium-sized black holes between these 2 extremes exist, but evidence has been hard to come by, with roughly a half-dozen candidates described so far.
A team led by astronomers at the University of Maryland and NASA’s Goddard Space Flight Center has found evidence for a new intermediate-mass black hole about 5,000 times the mass of the sun. The discovery adds one more candidate to the list of potential medium-sized black holes, while strengthening the case that these objects do exist. The current study used data from the European Space Agency’s XMM-Newton satellite.
The new intermediate-mass black hole candidate, known as NGC1313X-1, is classified as an ultraluminous X-ray source, and as such is among the brightest X-ray sources in the nearby universe. Some astronomers suspect that they are intermediate-mass black holes actively drawing in matter, producing massive amounts of friction and X-ray radiation in the process.
Against this backdrop of haphazard X-ray fireworks created by NGC1313X-1, Pasham etal identified 2 repeating flares, each flashing at an unusually steady frequency. One flashed about 27.6 times per minute and the other about 17.4 times per minute. Comparing these 2 rates yields a nearly perfect 3:2 ratio. This 3:2 ratio appears to be a common feature of stellar mass black holes and possibly intermediate-mass black holes as well. The flashes are most likely caused by activity close to the black hole, where extreme gravity keeps all surrounding matter on a very tight leash.
The 3:2 ratios can also provide an accurate measure of a black hole’s mass. Smaller black holes will flash at a higher frequency, while larger black holes will flash less often.
NASA plans to launch a new X-ray telescope, the Neutron Star Interior Composition Explorer (NICER), in 2016. Pasham has already identified several potential intermediate-mass black hole candidates that he hopes to explore with NICER.
http://www.prweb.com/releases/2015/09/prweb12972146.htm
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