For the first time scientists measure the spin rate of Super-massive black hole

March 1, 2013

Scientists, for the first time, have measured the spin rate of a super-massive black hole — and found it is rotating at nearly the speed of light.

How did they measure this?

Astronomers measured the spin rate of the super-massive black hole at the center of the spiral galaxy NGC 1365 by using new data from the Nuclear Spectroscopic Telescope Array, or NuSTAR, and the European Space Agency’s XMM-Newton X-ray satellites. A black hole’s gravity is so strong that, as the black hole spins, it drags the surrounding space along. The edge of this spinning hole is called the event horizon. Any material passing the event horizon is engulfed into the black hole. The spiraling matter collects into an accretion disk, where friction heats it and causes it to emit X-rays. Scientists measured X-rays from the center of NGC 1365 to determine where the inner edge of the accretion disk was located.

Why this measure of spin rate is important?

The physical aspects of a black hole are defined by only two numbers: mass and spin. By learning those two numbers, one can learn everything about the black hole. Most significantly, the black hole’s spin gives clues to its past and by extension the evolution of its host galaxy. Studying a super-massive black hole also allows researchers to verify Einstein’s theory of general relativity in extreme conditions.

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