- uploaded: Aug 4, 2012
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This tell-tale signal, called a quasi-periodic oscillation or QPO, is a characteristic feature of the accretion disks that often surround the most compact objects in the universe â€” white dwarf stars, neutron stars and black holes. QPOs have been seen in many stellar-mass black holes, and there is tantalizing evidence for them in a few black holes that may have middleweight masses between 100 and 100,000 times the sun's.
Until the new finding, QPOs had been detected around only one supermassive black hole â€” the type containing millions of solar masses and located at the centers of galaxies. That object is the Seyfert-type galaxy REJ 1034+396, which at a distance of 576 million light-years lies relatively nearby.
On March 28, 2011, NASA's Swift detected intense X-ray flares thought to be caused by a black hole devouring a star. In one model, illustrated here, a sun-like star on an eccentric orbit plunges too close to its galaxy's central black hole. About half of the star's mass feeds an accretion disk around the black hole, which in turn powers a particle jet that beams radiation toward Earth.
Credit: NASA's Goddard Space Flight Center/Conceptual Image Lab