Secrets of the galaxy discovered by Durham University experts

Durham University astronomers studying black holes have made a discovery which could lead to a greater understanding of galaxy growth

Artist’s impression of a supermassive black hole
Artist’s impression of a supermassive black hole

Experts from our region have made a discovery about ‘supermassive’ black holes which could lead to a better understanding of how they help galaxies grow.

Astronomers at Durham University observed a black hole – with mass 10 million times that of our Sun – at the centre of a spiral galaxy 500 million light years from Earth.

The scientists watched the black hole 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 say that understanding spin could lead to greater understanding of galaxy growth over billions of years.

Black holes lie at the centres 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.

Spin is difficult to measure as it only affects the behaviour of material really close to the black hole.

Lead researcher Professor Chris Done, in the department of physics, said: “We know the black hole in the centre 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 10m boulder, influencing something the size of the Earth.

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

“If a black hole is spinning, it drags space and time with it and that drags the accretion disc, containing the black hole’s food, closer towards it.

“This makes the black hole spin faster, a bit like an ice skater doing a pirouette.

“By being able to measure the distance between the black hole and the accretion disc, we believe we can more effectively measure the spin of black holes.

“Because of this, we hope to be able to understand more about the link between black holes and their galaxies.”

The Durham scientists were able to measure the spin of the black hole using soft x-ray, optical and ultra-violet images captured by the European Space Agency’s XMM-Newton satellite.

They said further research was needed to reduce the effects of black hole mass on their findings.

 

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