Imagine the Universe!

Taking Black Holes for a Spin

Early in 2001, Dr. Tod Strohmeyer (NASA/GSFC) discovered evidence for a rotating black hole. No one doubts that black holes rotate, but evidence for them has been elusive. Through careful analysis of data from the Rossi X-ray Timing Explorer, Dr. Strohmeyer found such evidence by examining how fast surrounding gas orbited the black hole. The videos presented here illustrate this property of a rotating black hole.

Black Hole in Binary Star System


Click on the image to view the video. (6 Mb QuickTime)
(Credit: NASA/Honeywell Max-Q Digital Group/Dana Berry)

In this video we see a black hole in a binary star system, with material from the blue giant star streaming towards the black hole. The gas in this stream orbits the black hole and forms a disk. Gas orbiting closer to the black hole moves faster than gas farther out. The gas heats up due to interaction of material moving at these different speeds, becoming hot enough to emit x-rays. Lines from the poles of the black hole represent jets of gas being ejected from the vicinity of the black hole at nearly the speed of light. How these jets form is poorly understood, but they are often seen near black holes accreting large amounts of material.

The gap between the gas disk and the black hole (seen near the end of the video) represents the innermost orbit matter can be in before plunging into the black hole. The radius of this innermost orbit depends on whether the black hole is rotating or not. If the black hole is rotating, material can orbit in more closely, causing the material to move faster than if the black hole is not rotating.

Space-time Near a Rotating Black Hole

Movie Movie
Click on either image to view the video. (6 Mb QuickTime)
(Credit: NASA/Honeywell Max-Q Digital Group/Dana Berry)

This video illustrates the difference between a spinning and non-spinning black hole. In each, lines of space-time are drawn around the event horizon. In the video, the event horizon is surrounded by a blue glow, which represents gas just before if falls past the event horizon. The innermost stable orbit is the ring of gas outside this blue glow. You can see that space-time is curved around the black hole which is rotating. As a consequence, around a rotating black hole the gas can be in a closer orbit.

Imagine the Universe is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

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Acting Project Leader: Dr. Barbara Mattson
All material on this site has been created and updated between 1997-2012.

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