Page last updated at 18:01 GMT, Wednesday, 4 March 2009

Dancing black hole twins spotted

Virgo cluster (SPL)
A giant amalgam of black holes sits at the centre of the Virgo galaxy cluster

Researchers have seen the best evidence yet for a pair of black holes orbiting each other within the same galaxy.

While such "binary systems" have been postulated before, none has ever been conclusively shown to exist.

The new black hole pair is dancing significantly closer than the prior best binary system candidate.

The work, published in the journal Nature, is in line with the theory of the growth of galaxies, each with a black hole at their centre.

The theory has it that as galaxies near one another, their central black holes should orbit each other until merging together.

But evidence for black holes nearing and orbiting has so far been scant.

Dancing cheek-to-cheek

As matter falls into black holes, it emits light of a characteristic colour that in turn gives information about the direction in which the black hole is moving.

In a binary system, two beams should be emitted, each a slightly different colour.

Twin black holes graphic
The black holes emit two beams, each a slightly different colour

Todd Boroson and Tod Lauer of the US National Optical Astronomy Observatory analysed some 17,500 spectra from the Sloan Digital Sky Survey, and have now found just such a pair of emissions coming from a distant quasar.

The researchers estimate that the two light sources come from black holes between 20 million and one billion times more massive than our Sun.

The black holes are separated by an estimated distance of less than a third of a light-year - cheek-to-cheek by black hole standards and significantly closer than the postulated binary system spotted by the Chandra X-ray Observatory in 2003.

The pair are estimated to dance around one another every 100 years.

Because they are moving with respect to the Earth as well as to each other, observations of their movement over the next few years should prove beyond question that they are indeed the first partnered pair of black holes.

"Previous work has identified potential examples of black holes on their way to merging, but the case presented by Boroson and Lauer is special because the pairing is tighter and the evidence much stronger," said Jon Miller, an astronomer at the University of Michigan.

Print Sponsor


SEE ALSO
Black holes 'preceded galaxies'
07 Jan 09 |  Science & Environment
Black hole confirmed in Milky Way
09 Dec 08 |  Science & Environment
Black hole star mystery 'solved'
23 Aug 08 |  Science & Environment
Black holes on collision course
19 Nov 02 |  Science/Nature
New support for black hole theory
15 Apr 04 |  Science & Environment

RELATED INTERNET LINKS
The BBC is not responsible for the content of external internet sites


FEATURES, VIEWS, ANALYSIS
Has China's housing bubble burst?
How the world's oldest clove tree defied an empire
Why Royal Ballet principal Sergei Polunin quit

BBC navigation

BBC © 2013 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.

Americas Africa Europe Middle East South Asia Asia Pacific