Why Do Black Holes And Galaxies Spin?

The team of astronomers observed a black hole – with a mass 10 million times that of our Sun – at the center of a spiral galaxy 500 million light years from Earth while it was feeding on the surrounding disc of material that fuels its growth and powers its activity.

By viewing optical, ultra-violet and soft x-rays generated by heat as the black hole fed, they were able to measure how far the disc was from the black hole.

This distance depends on black hole spin as a fast spinning black hole pulls the disc in closer to itself, the researchers said. Using the distance between the black hole and the disc, the scientists were able to estimate the spin of the black hole.

The scientists said that understanding spin could lead to greater understanding of galaxy growth over billions of years.

Black holes lie at the centers of almost all galaxies, and can spit out incredibly hot particles at high energies that prevent intergalactic gases from cooling and forming new stars in the outer galaxy. Scientists don’t yet understand why the jets are ejected into space, but the Durham experts believe that their power could be linked to the spin of the black hole. This spin is difficult to measure as it only affects the behavior of material really close to the black hole.

An artist’s impression of a supermassive black hole at the centre surrounded by matter flowing onto the black hole in what is termed an accretion disk. Also shown is an outflowing jet of energetic particles, believed to be powered by the black hole’s spin.