Astronomers put forward new theory on size of black holes
Issued by University of Leicester Press Office on 23 March 2012
Movie simulations can be found here: http://www.astro.le.ac.uk/~cjn12/tilt.shtml
Figures are available in the original paper: http://www.astro.le.ac.uk/~cjn12/papers/twist.pdf
Astronomers have put forward a new theory about why black holes become so hugely massive – claiming some of them have no ‘table manners’, and tip their ‘food’ directly into their mouths, eating more than one course simultaneously.
Researchers from the UK and Australia investigated how some black holes grow so fast that they are billions of times heavier than the sun.
The team from the University of Leicester (UK) and Monash University in Australia sought to establish how black holes got so big so fast. Their research is due to published in the Monthly Notices of the Royal Astronomical Society.
The research was funded by the UK Science and Technology Facilities Council.
Professor Andrew King from the Department of Physics and Astronomy, University of Leicester, said: “Almost every galaxy has an enormously massive black hole in its centre. Our own galaxy, the Milky Way, has one about four million times heavier than the sun. But some galaxies have black holes a thousand times heavier still. We know they grew very quickly after the Big Bang.’’
“These hugely massive black holes were already full--grown when the universe was very young, less than a tenth of its present age.”
Black holes grow by sucking in gas. This forms a disc around the hole and spirals in, but usually so slowly that the holes could not have grown to these huge masses in the entire age of the universe. `We needed a faster mechanism,' says Chris Nixon, also at Leicester, “so we wondered what would happen if gas came in from different directions.”
Nixon, King and their colleague Daniel Price in Australia made a computer simulation of two gas discs orbiting a black hole at different angles. After a short time the discs spread and collide, and large amounts of gas fall into the hole. According to their calculations black holes can grow 1,000 times faster when this happens.
“If two guys ride motorbikes on a Wall of Death and they collide, they lose the centrifugal force holding them to the walls and fall,” says King. The same thing happens to the gas in these discs, and it falls in towards the hole.
This may explain how these black holes got so big so fast. “We don't know exactly how gas flows inside galaxies in the early universe,” said King, “but I think it is very promising that if the flows are chaotic it is very easy for the black hole to feed.”
The two biggest black holes ever discovered are each about ten billion times bigger than the Sun.
Note to newsdesk: For more information, contact Professor Andrew King on firstname.lastname@example.org
The Science and Technology Facilities Council is keeping the UK at the forefront of international science and tackling some of the most significant challenges facing society such as meeting our future energy needs, monitoring and understanding climate change, and global security.
The Council has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar.
STFC operates or hosts world class experimental facilities including:
• in the UK; ISIS pulsed neutron source, the Central Laser Facility, and LOFAR. STFC is also the majority shareholder in Diamond Light Source Ltd.
• overseas; telescopes on La Palma and Hawaii
It enables UK researchers to access leading international science facilities by funding membership of international bodies including European Laboratory for Particle Physics (CERN), the Institut Laue Langevin (ILL), European Synchrotron Radiation Facility (ESRF) and the European Southern Observatory (ESO).
STFC also has an extensive public outreach and engagement programme. It is using its world leading research to inspire and enthuse schools and the general public about the impact and benefits that science can have on society.
STFC is one of seven publicly-funded research councils. It is an independent, non-departmental public body of the Department for Business, Innovation and Skills (BIS).
Follow us on Twitter @STFC_Matters