Perhaps the only thing weirder than a black hole is a spinning black hole (see Discover, July 2002, page 32), yet astronomers are quickly stripping the mystery from these objects. In the latest twist, a team led by Jane Turner of NASA's Goddard Space Flight Center has found new evidence that light escaping from the edge of a black hole loses energy while climbing the gravitational well created by the black hole's spin, as predicted by Einstein's general theory of relativity.
The astronomers used the orbiting Chandra and XMM-Newton X-ray observatories to detect spikes of radiation emitted by energetic iron atoms near the event horizon, the point beyond which nothing can escape a black hole's grip. The spikes originate from hot spots in a luminous disk of gas around a monster black hole—as massive as 20 million suns—in the center of the galaxy NGC 3516. These X-ray observations will allow astronomers to measure whether the hole is indeed spinning and dragging space-time with it. That information, says Turner, will help astronomers attain a better understanding of how relativity influences matter and space under extreme conditions.
What a black hole looks like, maybe.Photograph courtesy of NASA/GSFC.
