Scientists Measure Invisible Black Hole's Spin With New Technique

Despite never having actually seen one, scientists seem to learn something new everyday about black holes — today it's a new technique for measuring the spin of a black hole.

Researchers from Durham University were able to figure out how to calculate the spin of a supermassive black hole with 10 million times the mass of the sun at the heart of a galaxy 500 light-years away using a combination of soft x-ray, optical, and ultra-violet images. They claim the key lies in measuring the distance between the black hole and its accretion disk, the swirl of matter surrounding a black hole.

"We know the black hole in the center of each galaxy is linked to the galaxy as a whole, which is strange because black holes are tiny in relation to the size of a galaxy. This would be like something the size of a large boulder [10m], influencing something the size of the Earth," said Chris Done from the Department of Physics at Durham University, the key facility involved in the research.

"Understanding this connection between stars in a galaxy and the growth of a black hole, and vice-versa, is the key to understanding how galaxies form throughout cosmic time."

Measuring the spin of something you can't see, and something that behaves rather abnormally, can be tough, but the team is confident that the data is important enough to pursue. The spin, for instance, could one day help explain why black holes shoot out jets of matter that can measure light-years long.

You can read the full published study in the Oxford University Press journal Monthly Notices of the Royal Astronomical Society.