Wednesday, January 16, 2008

Spinning Black Holes

Results from NASA's Chandra X-ray Observatory, combined with new theoretical calculations, provide one of the best pieces of evidence yet that many supermassive black holes are spinning extremely rapidly.

The images below show 4 out of the 9 large galaxies included in the Chandra study, each containing a supermassive black hole in its center.

The Chandra images show pairs of huge bubbles, or cavities, in the hot gaseous atmospheres of the galaxies, created in each case by jets produced by a central supermassive black hole. Studying these cavities allows the power output of the jets to be calculated. This sets constraints on the spin of the black holes when combined with theoretical models.

The Chandra images were also used to estimate how much fuel is available for each supermassive black hole, using a simple model for the way matter falls towards such an object. The artist's impression on the right side of the main graphic shows gas within a "sphere of influence" falling straight inwards towards a black hole before joining a rapidly spinning disk of matter near the center.

Most of the material in this disk is swallowed by the black hole, but some of it is swept outwards in jets (coloured blue) by quickly spinning magnetic fields close to the black hole.

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