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Spinning black hole sprays light-speed plasma clouds into space

Published: 29 April 2019
V404 Cygni
Artist's impression of the V404 Cygni black hole X-ray binary system. Credit: ICRAR

An international research team, including scientists from the University of Southampton have discovered rapidly swinging jets shooting from a black hole 8000 light years from Earth. The new findings could shed new light on how black holes shape the universe’s galaxies.

Matter from an orbiting star can be fed into a black hole via a process known as accretion. As black holes feed, they also spit out material in the form of jets of hot gas travelling close to the speed of light. It had been assumed that such jets travelled in a straight line but the team have for the first time seen jets that appear to be rapidly rotating, firing out material at high speed - potentially just minutes apart.

These findings, published in the scientific journal Nature, provide scientists with a greater understanding of how accretion works and how black holes inject energy into the space around them as the jets dump matter over a far larger area than they would by only travelling in a straight line.  If large, ‘supermassive’ black holes in the middle of galaxies behave in the same way, then their jets might impact on the galaxy by instigating, or turning off the formation of stars.

The research team was led by Associate Professor James Miller-Jones of the International Centre for Radio Astronomy Research (ICRAR) in Australia and included Dr Matt Middleton and Dr Diego Altamirano from the Physics and Astronomy department at the University of Southampton. They began studying a black hole in our Galaxy – in the V404 Cygni system - which began feeding at an incredible rate in 2015.

Associate Professor Miller-Jones said “This is one of the most extraordinary black hole systems I’ve ever come across,” he said.

“Like many black holes, it’s feeding on a nearby star, pulling gas away from the star and forming a disk of material that encircles the black hole and spirals towards it under gravity.

“What’s different in V404 Cygni is that we think the disk of material and the black hole are misaligned.

“This appears to be causing the inner part of the disk to wobble like a spinning top and fire jets out in different directions as it changes orientation.

“You can think of it like the wobble of a spinning top as it slows down—only in this case, the wobble is caused by Einstein’s theory of general relativity.”

Because of the very bright outburst from the black hole, telescopes around the world tuned in to study what was going on. Unlike the many other groups studying the same black hole, the team were able to observe it down to a much smaller size-scale by using a system of 10 radio telescopes dotted around the world.

Dr Matt Middleton at the University of Southampton had been developing the theory which takes Einstein’s General Relativity and predicts how long it should take the jets to rock back and forth. This was used in the current work to try and gauge the properties of the phenomenon.  

Dr Middleton said: "Although we can't directly see the inner regions in these black hole binaries, the motion of the jets in this system reveals the inner workings of accretion on the black hole's doorstep where relativity has a profound effect on light and matter."

 

An animation of the precessing jets and accretion flow in V404 Cygni narrated by Associate Professor James Miller-Jones of Curtin University and ICRAR. Zooming in from the high-speed plasma clouds observed with our radio telescope, we see the binary system itself. Mass from the star spirals in towards the black hole via an accretion disk, whose inner regions are puffed up by intense radiation. The spinning black hole pulls spacetime (the green gridlines) around with it, causing the inner disk to precess like a spinning top, redirecting the jets as it does so. Credit: ICRAR

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