NEWS & PRESS
Astronomers have found a new way of measuring the spin in supermassive black holes, which could lead to better understanding about how they drive the growth of galaxies. The scientists at Durham University, UK, publish their work in a paper in the Oxford University Press journal Monthly Notices of the Royal Astronomical Society.
The team of astronomers observed a black hole - with a mass 10 million times that of our Sun - at the centre 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 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. This 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, at Durham University, 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 boulder (10m), 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 the 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.
Professor Chris Done (on Monday 30 July and Tuesday 31 July)
Durham University Media Relations Office
Image and caption
An image is available from https://www.ras.org.uk/images/stories/press/black%20hole%20spin%20courtesy%20of%20nasa-jpl-caltech.jpg
Caption: 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. Image credit (NASA/JPL-Caltech).
The research was funded by the Science and Technology Facilities Council: www.stfc.ac.uk
The UK, led by Leicester and supported by STFC, played a major role in the development of the instrumentation for the mission. Further UK involvement included University College London and the University of Birmingham. Ongoing support for the operation of XMM-Newton is funded by the UK Space Agency. UKSA works with STFC which funds researchers to exploit the scientific data yielded by this cornerstone mission.
It appears in: "A new way to measure supermassive black hole spin in accretion disc dominated Active Galaxies, Done C, et al, Monthly Notices of the Royal Astronomical Society, in press. The paper is available from the Durham University Media Relations Office, or after the embargo expires from http://dx.doi.org/10.1093/mnras/stt1138
Notes for editors
Durham University Department of Physics: www.dur.ac.uk/physics/
Professor Chris Done staff profile: www.dur.ac.uk/physics/research/groups/?mode=staff&id=1746
Durham University is a world top-100 university with a global reputation and performance in research and education. The most recent UK league tables place Durham in the top echelon of British universities academically. Durham is ranked in the top 5 UK universities in the influential Sunday Times University Guide 2013; is 26th in the world for the impact of its research (THE citations ratings) and 20th in the world for the employability of its students by blue-chip companies world-wide. We are a residential Collegiate University: England's third oldest university and at our heart is a medieval UNESCO World Heritage Site, of which we are joint custodians with Durham Cathedral. Durham is a member of the Russell Group of leading research-intensive UK universities. www.durham.ac.uk
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