Artist view of active nucleus of NGC 4151 with solar system orbits for scale
Credit: NASA's Goddard Space Flight Center; A. Zoghbi et al.; XMM-Newtion/ESA

Echolocating a Black Hole

Actively feeding supermassive black holes at the centers of some galaxies produce some of the most energetic and violently variable phenomena we know about. These black holes produce enormous jets of particle beams, along with high energy gamma-ray and X-ray radiation. The means by which these black holes feed, and indeed the geometry of the spacetime around these objects, is a subject of much interest and debate. Now, a careful and clever analysis of observations by the XMM-Newton X-ray observatory of an active galaxy called NGC 4151 has, for the first time, helped astronomers test the source of some of the emission down to distance of a few times the black hole's size. This analysis used the "echo" of flares of X-ray radiation emitted near the black hole to define the structure of the material very close to the black hole. The image above shows an artist rendition of the central black hole in NGC 4151, with a bright X-ray source above the black hole (possibly associated with the base of a particle beam) shown as a blue ball. A sudden brightening of this emitting source lights up the inner part of the black hole's accretion disk, allowing astronomers in effect to "see" this structure by the time-delayed reflection of the monster's X-rays. To give a sense of scale, the artist has imagined the black hole being orbited by the planets in our solar system. The black hole, which generates power on a cosmic scale and has the equivalent mass to 50 million suns, is actually tiny, probably smaller than the orbit of the earth around the Sun.
Published: June 4, 2012

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Page Author: Dr. Michael F. Corcoran
Last modified Tuesday, 31-May-2022 11:27:33 EDT