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AAO Press Releases

Tuesday, 2 March 1999

 

Southern Cosmic Census creates the largest map of the universe

Astronomers have created the largest map of the Universe using the Anglo-Australian Telescope, in NSW, Australia and there is much more to come. The scientists are using the 2dF (Two-degree field) instrument on the 3.9-metre Anglo-Australian Telescope (the largest optical telescope in Australia). Researchers are only part way through their work, and are planning to make the map 10 times as big.

So far the 2dF Galaxy Redshift Survey has pinpointed 30 000 galaxies. Astronomers plan to produce an extremely detailed three-dimensional map of the Southern heavens.  The companion survey of distant quasars has now passed 3 000 quasars, and is twice as large as the previous largest quasar survey. 

Dr Matthew Colless of the Australian National University’s Mount Stromlo and Siding Spring Observatory, and Professor Richard Ellis of the Institute of Astronomy at the University of Cambridge (co leaders of the large group of Australian and British astronomers who are conducting the galaxy Redshift research) said they were delighted with the progress of project.
 
 "We have been planning this survey for almost ten years, and as the results come flooding in our ambitious goals are being fulfilled. At this rate, we will have no problems completing our survey by 2001."
 
Researchers are looking for the redshifts of 250 000 galaxies and 25 000 quasars. Redshifts give astronomers an idea of how far away a galaxy or quasar is. This enables them to build up a real three-dimensional picture of the Universe, rather than the two dimensional view we see on the sky. By mapping quasars, astronomers can survey parts of the very distant Universe at the same time as nearer galaxies. 

Dr Brian Boyle, Director of the Anglo-Australian Observatory, and leader of the team of astronomers conducting the 2dF Quasar Redshift Survey said the surveys are of great international importance."Many astronomers rely on cosmic censuses for their work. In the past, information has been gleaned from 'flat' two-dimensional maps on the sky.  We are now entering the era when large 3D-maps of the Universe will be routinely available via the Internet. These will be used by astronomers to test out their cosmological theories -- or simply for the general public to go on virtual billion-light-year flights to the outer limits of the Universe.”

The 2dF is one of the most complex astronomical instruments ever constructed. It took seven years to perfect, and was built in-house at the Anglo-Australian Observatory. The 2dF uses optical fibres to enable 400 objects to be observed simultaneously. Once astronomers have chosen the galaxies and quasars to be observed, and the details are fed into a computer, an amazingly quick and accurate robotic arm places each fibre in exactly the right position to collect the light. 

Dr Karl Glazebrook, instrument scientist for 2dF at the Anglo Australian Observatory said, "The largest structures in the known Universe are huge filaments of galaxies, perhaps a billion light years long. These structures are remnants of microscopic quantum fluctuations in the fireball from which the Universe sprang in the Big Bang. We need to survey a huge volume of space, like a cube several billion light years along each side, to understand how common such structures are. This tells us about the conditions in the primeval Universe and even about the laws of physics themselves. The 2dF survey is the first which will be big enough to address these questions".
 
Large-scale surveys such as this one not only give an idea of the structure of a large chunk of the Universe but the results will be used by other astronomers for years to come.
 
Dr Colless and Dr Ellis praised the team that is making the project come to fruition. "This project is only possible due to the cooperation of dozens of people around the world. In the UK scientists are working with the data via the Internet as the observations are being carried out in Australia.” 

Image available 
http://msowww.anu.edu.au/~iap/useful.html     cone_pr.ps
 

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© Anglo-Australian Observatory 2004, PO Box 296, Epping NSW 1710 Australia

Roger Bell rb@aaoepp.aao.gov.au

2 March 1999