Prof. Brian Boyle
Director, Anglo-Australian Observatory
P.O. Box 296, Epping, NSW 2121, Australia
Tel.: +61-2-9372-4811
Fax: +61-2-9372-4880
Dr Shaun Cole
Dept of Physics, University of Durham
Science Laboratories, South Road, Durham DH1 3LE, United Kingdom Email:
Tel.: +44-191-374-2103
Fax: +44-191-374-3749
Dr Matthew Colless
Research School of Astronomy & Astrophysics
The Australian National University
Weston Creek, Canberra, ACT 2611, Australia
Tel.: +61-2-6279-8030
Fax: +61-2-6249-0260
Dr Gavin Dalton
Dept of Physics & Astrophysics, University of Oxford
Keble Road, Oxford OX1 3RH, United Kingdom
Tel.: +44-1865-273310
Fax: +44-1865-273390
Prof. Richard Ellis
Astronomy Dept, California Institute of Technology
105-24 Caltech, 1201 East California Blvd, Pasadena CA 91125, USA Email:
Tel.: +1-626-395-2598
Fax: +1-626-568-9352
Prof. Carlos Frenk
Dept of Physics, University of Durham
Science Laboratories, South Road, Durham DH1 3LE, United Kingdom Email:
Tel.: +44-191-374-2141
Fax: +44-191-374-3749<
Prof. Karl Glazebrook
Department of Physics & Astronomy, Johns Hopkins University
3400 North Charles Street, Baltimore, MD 21218-2686, USA
Tel.: +1-410-516-6785
Fax: +1-410-516-7239
Dr Steve Maddox
School of Physics & Astronomy, University of Nottingham
Nottingham NG7 2RD, United Kingdom
Tel.: +44-115-951-5133
Fax: +44-115-951-5180
Prof. John Peacock
Institute for Astronomy, University of Edinburgh
Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, United Kingdom Email:
Tel.: +44-131-668-8100
Fax: +44-131-668-8416
Dr David Weinberg
Department of Astronomy, Ohio State University
McPherson Laboratory, 140 West 18th Ave, Columbus OH 43210-1173, USA Email:
Tel.: +1-614-292-6543
Fax: +1-614-292-2928

The largest survey of galaxies ever conducted has resulted in the most spectacular three-dimensional map of the Universe to date.
An international team of astronomers has just completed a two-year survey (the 2dF Galaxy Redshift Survey) of 100,000 galaxies — four times more than the previous such survey.
The team, coordinated by Dr Matthew Colless of the Australian National University and Prof. John Peacock of Edinburgh University, announced their results today at the Rochester, New York, meeting of the American Astronomical Society (AAS).
"Our final goal is to survey 250,000 galaxies," said Dr Colless. "So reaching 100,000 galaxies is a major milestone."
The survey reveals a cosmos containing long filamentary chains of galaxies, giant superclusters and enormous empty voids up to 200 million light years across. It also provides new evidence that the low density of the Universe will cause it to expand forever, rather than collapse in a "Big Crunch" (the opposite of the Big Bang with which it began).
The team today showed a simulated "Trip through the Universe" created using the real positions of galaxies measured during the survey. Professor Matthew Bailes from Swinburne University in Australia led the group who constructed the simulation using 300 hours of computer time.
"Most of us are used to the Hollywood versions of travelling through the Universe, but this version is much closer to the truth," said Professor Bailes. "We have used the information from the survey and combined it with actual photographs of galaxies."
The map produced by the British, Australian and US astronomers covers 1/20th of the whole sky and reaches to a depth of 4 billion light years.
"The sheer volume of space we cover is vast, about 13 billion billion billion cubic light years," said Prof. Karl Glazebrook from Johns Hopkins University, representing the American members of the team here today at the AAS. "To get an idea how big that is, imagine replacing every atom in the Sun with New York’s Manhattan Island. That would just about fill this volume."
A new instrument — the Two Degree Field (2dF) spectrograph on the Anglo-Australian Telescope (AAT) in New South Wales, Australia — made the giant survey possible.
The 2dF spectrograph has a field of view of two degrees on the sky (about 4 times the diameter of the full moon — the largest field of view of any large telescope) and can survey 400 galaxies simultaneously. Light from the galaxies is directed into the spectrograph through optical fibers.
"The 2dF spectrograph is a very innovative instrument," said the Director of the Anglo-Australian Observatory, Prof. Brian Boyle. "It uses a robot arm to place each optical fiber in precisely the right position to collect light from a single galaxy. The robot positions 400 fibers every hour throughout the night. In one night we can measure the distances to over 3000 galaxies."
The image of the Universe now revealed shows a wealth of detail. "This map is simply incredible. For the first time you can see the structure of the Universe in a truly enormous volume as delineated by over one hundred thousand galaxies, each like our own Milky Way. It’s a tremendous observational achievement, made possible by a remarkably clever and efficient instrument," commented Professor Richard Ellis, Caltech, who with colleagues in the UK and Australia first proposed the survey 10 years ago.
"The seeds for these colossal structures originated on sub-atomic scales in the first instants of time, when the expanding universe began. There were small ripples in the density of matter, which can still be seen in the Cosmic Microwave Background," said John Peacock. "Over more than 10 billion years, gravity amplified the ripples, causing galaxies and superclusters to grow. When the survey is complete, cosmologists will be able for the first time to link the distant past directly to the modern Universe. This is the primary mission of the 2dF survey."
Dr Gavin Dalton from Oxford University announced the new measurement of the amount of matter in the Universe at the AAS.
"The idea is quite simple," he said. "Near large concentrations of galaxies, the expansion of the Universe is slowed down by the galaxies’ gravitational pull. This allows us to estimate the mass of these concentrations. By analyzing the whole survey we can directly measure the mass of the Universe".
Dr Shaun Cole from the University of Durham in England said "For the first time we can clearly see in maps constructed from the survey the effect of the gigantic gravitational pull of galaxy clusters. What we see includes the effect of any dark matter in them as well. Such effects were predicted by theorists over a decade ago and our survey provides a beautiful confirmation of the importance of dark matter in the Universe. The data so far are consistent with our universe falling well short of the mass density required to arrest its current expansion. Our measurements are already the most precise ever, and will only get better as the survey proceeds."
"In 1998, studies of distant exploding stars called supernovae showed that the expansion of the Universe was accelerating," Professor Glazebrook elaborated. "Earlier this year, the Boomerang experiment looking at the Cosmic Microwave Background showed we lived in a ‘flat’ Universe."
"Now the 2dF Galaxy Redshift Survey shows that the amount of matter in the Universe is far too low to cause flatness. The deficit must be made up by what is known as ‘vacuum energy’, which is predicted by quantum physics to fill empty space. This would cause the expansion to accelerate," he said.
"These results support each other, and point towards a model where two-thirds of the energy in the Universe comes from the vacuum of empty space, paradoxical though it may sound. The fate of the Universe is to expand faster and faster, forever."
The 2dF Galaxy Redshift Survey is on course to be completed by the end of 2001. The 100,000 redshifts being presented today will be publicly released worldwide in early 2001. When the 2dF survey is complete, the team will be able to measure with fine precision the tiny fluctuations in galaxy densities on scales of 400 million light years — the same scales that are observed in the microwave background 13 billion years ago.
Following closely on the heels of the 2dF Galaxy Redshift Survey is the even more ambitious Sloan Digital Sky Survey, which aims to measure redshifts for one million galaxies over a 5-year period.
"This announcement marks a big advance in galaxy redshift surveys," said David Weinberg, an astronomer at Ohio State University and a member of the Sloan collaboration. "The largest redshift survey of the 1990s had 25,000 galaxies, enough to reveal these enormous structures, but still a low 5-digit number."
"The 2dF team has broken the 6-digit barrier, and that means they can measure these structures with enough precision to understand their origin. Giant redshift surveys like 2dF and Sloan will transform the study of large scale structure into a precision science."
"The competition is healthy," said Dr Colless. "Every scientific result needs independent confirmation and cross-checking. When you are talking about the fate of the Universe, a second opinion is essential!"
For materials related to videos and photographs:
Roger Bell
Press Officer, Anglo-Australian Observatory
P.O. Box 296, Epping, NSW 2121, Australia
Tel.: +61-2-9372-4865
Fax: +61-2-9372-4880
For information on the creation of the 2dF fly-through movie:
Christopher Fluke
Centre for Astrophysics and Supercomputing
Swinburne University of Technology
Mail 31, P.O. Box 218, Hawthorn, Victoria 3122, Australia
Tel.: +61-3-9214-5828
Fax: +61-3-9214-8797
Web resources:
* 2dF Galaxy Redshift Survey
* Boomerang cosmic microwave background measurements
* Supernovae cosmology
* Sloan Digital Sky Survey
[Image 1]
The ‘Cosmic Web’ revealed by 2dF
[Image 2]
Simulated fly-through of the 2dF Universe created by Swinburne University
[Image 3]
Gravitational distortion from clusters is evident in the galaxy distribution on scales of 150 million light years — but not enough to close the Universe.