Rapidly Whirling Black Holes Discovered Spinning at Near Maximum Speed

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 on the left 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. The result of this calculation sets constraints on the spin of the black holes when combined with theoretical models.

The Chandra images also were 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 inward 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 outward in jets (colored blue) by quickly spinning magnetic fields close to the black hole.

Previous work with these Chandra data showed that the higher the rate at which matter falls towards these supermassive black holes, the higher their power output is in jets. However, without detailed theory the implications of this result for black hole behavior were unclear. The new study uses these Chandra results combined with leading theoretical models for the production of jets, plus general relativity, to show that the supermassive black holes in these galaxies must be spinning at close to the maximum rate. If black holes are spinning at this limit, material can be dragged around them at close to the speed of light -- the speed limit resulting from Einstein's theory of relativity.

Credit: X-ray: NASA/CXC, Illustration: CXC/M. Weiss

10 January 2008 — A new study using results from NASA's Chandra X-ray Observatory provides one of the best pieces of evidence yet that many supermassive black holes are spinning extremely rapidly, according to a research team led by a Penn State astronomer. The whirling of these giant black holes drives powerful jets that pump huge amounts of energy into their environment and affects the growth of galaxies.

"We think these monster black holes are spinning close to the limit set by Einstein's theory of relativity, which means that they can drag material around them at close to the speed of light," said Rodrigo Nemmen da Silva, a visiting graduate student at Penn State and the lead author of a paper on the new results, which will be presented on January 10, 2008 at the meeting of the American Astronomical Society in Austin, Texas. "Conditions around a stationary black hole are extreme, but around a rapidly spinning one would be even worse," Nemmen said.

The research team compared data from the Chandra observatory with leading theories of jets produced by rotating supermassive black holes. A sampling of nine giant galaxies that exhibit large disturbances in hot gas around them showed that the central black holes in these galaxies must be spinning at near their maximum rates.

The research reinforces other methods previously used, which have indicated that some stellar and supermassive black holes are spinning rapidly. According to Einstein's theory, a rapidly spinning black hole makes space itself rotate. This effect, coupled with gas spiraling toward the black hole, can produce a rotating, tightly wound vertical tower of magnetic field that flings a large fraction of the inflowing gas away from the vicinity of the black hole in an energetic, high-speed jet.

Computer simulations by other authors have suggested that black holes may acquire their rapid spins when galaxies merge, and through the accretion of gas from their surroundings. "Extremely fast spin might be very common for large black holes," said co-investigator Richard Bower of Durham University in the United Kingdom. "This might help us explain the source of these incredible jets that we see stretching for enormous distances across space."

One significant consequence of powerful, black-hole jets in galaxies in the centers of galaxy clusters is that they can pump enormous amounts of energy into their environments and heat the gas around them. This heating prevents the gas from cooling and it affects the rate at which new stars form, thereby limiting the size of the central galaxy. Understanding the details of this fundamental feedback loop between supermassive black holes and the formation of the most massive galaxies remains an important goal in astrophysics.

CONTACTS

Rodrigo Nemmen da Silva: (via PIO at AAS meeting) 617-721-6757, (Penn State office) 814 863 7260, rnd10@psu.edu

Megan Watzke (Chandra PIO attending the AAS meeting in Austin): (cell)617-721-6757, (office)617/496-7998), mwatzke@cfa.harvard.edu

Barbara K. Kennedy (PIO at Penn State): 814-863-4682, science@psu.edu

MORE INFORMATION

Additional information and images are available at: http://chandra.harvard.edu and http://chandra.nasa.gov. NASA's Marshall Space Flight Center, Huntsville, Alabama, manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Massachusetts.