Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Black holes’ fatal attraction triggers galaxies’ change of heart

05.08.2002



Supermassive black holes at the hearts of large galaxies merge when their host galaxies do, say Professor David Merritt of Rutgers University, New Jersey, and Professor Ron Ekers of CSIRO’s Australia Telescope National Facility in Sydney, Australia.

The astronomers make their claim in a paper published online in Science Express on August 1 [U.S. time].

Merritt and Ekers’ model is the strongest evidence to date that the black holes’ mutual attraction ends in an embrace rather than an endless waltz.



Simulations show that when large galaxies merge, interactions between the black holes and stars will make the black holes sink towards the centre of the combined galaxy. But as they approach the centre the black holes will kick out nearby stars, switching off the mechanism that was drawing them together.

"Most astronomers assume that nature finds a way to bring the black holes together, since we don’t see strong evidence of binary black holes at the centres of galaxies," says David Merritt. "We now have solid evidence that the black hole mergers actually take place."

That ’smoking gun’ evidence comes from powerful galaxies that shoot ’jets’ of radio-emitting particles from their cores.

Jets signal the presence of a supermassive black hole, millions or billions of times more massive than the Sun. The jets emerge, not from the black hole itself, but from a disk of gas and dismembered stars whirling around it.

About 7% of these galaxies look like their jets have suddenly changed direction. Jets are aligned with the spin axis of the black hole, astronomers think.

"Flipped jets suggest that the black hole has suddenly been realigned," says Ron Ekers.

Which is just what would happen if two black holes fused, the astronomers say. They show for the first time that even a small black hole can pack quite a punch, knocking another hole up to five times more massive through a large angle.

The idea of black-hole mergers is not new: British cosmologist Martin Rees raised it in a 1978 paper in the journal Nature, for example. But at that time it was too speculative to be taken seriously, Ron Ekers says.

Theorists still can’t explain what draws the black holes together once they have thrown the stars out of their neighbourhood. But when the gulf between the merging holes has shrunk to the size of the solar system, the holes start to radiate away energy as gravity waves, says David Merritt. Then the holes slide inexorably towards fusion, spiralling together faster and faster. Their final clinch releases an enormous burst of gravitational radiation.

The number of radio galaxies with flipped jets, plus the estimated 100-million-year lifetime of the ’radio lobes’ they produce, suggests that these cosmic takeovers happen at the rate of one a year, say Merritt and Ekers. That’s good news for those planning gravity-wave instruments to detect them.

For more information:

Professor David Merritt
Rutgers University
+1-732-445-5742 (office)
merritt@physics.rutgers.edu

Professor Ron Ekers
CSIRO Australia Telescope National Facility
+61-2-6790-4000 (1-2 August only)
0419-146-313 (mobile) or +61-419-146-313 from outside Australia
+61-2-9372-4300 (office, Australia)
Ron.Ekers@csiro.au

Helen Sim, Communications Manager
CSIRO Australia Telescope National Facility
+61-2-9372-4251 (office)
+61-419-635-905 (mobile)
Helen.Sim@csiro.au

Joseph Blumberg, Manager of Science Communications
Rutgers University
+1-732-932-7084 ext. 652 (office)
+1-732-356-3601 (home)
blumberg@ur.rutgers.edu

Rosie Schmedding | EurekAlert!
Further information:
http://www.sciencemag.org/sciencexpress/recent.shtml

More articles from Physics and Astronomy:

nachricht Ultra-compact phase modulators based on graphene plasmons
27.06.2017 | ICFO-The Institute of Photonic Sciences

nachricht Smooth propagation of spin waves using gold
26.06.2017 | Toyohashi University of Technology

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Touch Displays WAY-AX and WAY-DX by WayCon

27.06.2017 | Power and Electrical Engineering

Drones that drive

27.06.2017 | Information Technology

Ultra-compact phase modulators based on graphene plasmons

27.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>