The missing link between the Big Bang and the structure of the modern universe has been found by a team of British and Australian astronomers.

The discovery has emerged from a mammoth 10-year effort to map and measure the distribution of 220,000 galaxies by the 2dFGRS (2-degree Field Galaxy Redshift Survey), a consortium of astronomers using the 3.9-m Anglo-Australian Telescope (AAT) at Coonabarabran in NSW.

The survey revealed subtle features - ranging in size from 100 million to 1 billion light years - in the large-scale structure of the universe, confirming that galaxies are not evenly spread out across it but occur in subtle "lumps" and "wiggles".

"There is a definite pattern," says Professor Warrick Couch, a prominent UNSW astronomer who was part of the team. Professor Couch was recently appointed as of Head of the UNSW School of Physics.

The wiggles in the maps are remnants of ripples that permeated space soon after the Big Bang 14 billion years ago, destabilising the initial mist of matter, Professor Couch says.

"They show that the large-scale structure was set by physical processes that operated when the universe was very young indeed."

At the moment of its birth, the universe contained tiny irregularities that are thought to have resulted from quantum or subatomic processes, says Dr Shaun Cole of the University of Durham, who led the team.

"These irregularities have been amplified by gravity ever since and eventually gave rise to the galaxies we see today," Dr Cole says.

Independent corroboration of the 2dFGRS result was simultaneously announced by the US-led Sloan Digital Sky Survey (SDSS).

The SDSS team used a sample of 46,000 highly luminous red galaxies and a different method of analysis from the 2dFGRS team's.

"Happily, the two groups' conclusions are consistent," said 2dFGRS team member Dr Joss Hawthorn of the Anglo-Australian Observatory.

Theorists in the 1960s suggested that the primordial seeds of galaxies should be seen as ripples in the Cosmic Microwave Background (CMB) radiation emitted when the Universe was a mere 350,000 years old.

Ripples were subsequently seen in 1992 by NASA's COBE satellite but until now no firm link could be made with galaxies.

Professor Carlos Frenk, Director of the Institute for Computational Cosmology of the University of Durham said: "They establish a direct evolutionary link to the Big Bang. Finding them is a milestone in our understanding of how the cosmos was formed."

The 2dFGRS also showed that all the mass in the universe is outweighed by four to one by an even more exotic component called "vacuum energy" or "dark energy".

Professor Michael Strauss from Princeton University, spokesman for the SDSS collaboration said: "This is wonderful science. The two groups have now independently seen direct evidence for the growth of structure by gravitational instability from the initial fluctuations seen in the cosmic microwave background."

IMAGES

http://www.aao.gov.au/press/2dfgrs_wiggles.html

DID YOU KNOW?

UNSW's space science researchers are ranked independently to be in the world's top 1% in their field by total citations in the ISI Essential Science Indicators. See the link below -

http://www.in-cites.com/institutions/UnivNewSouthWales.html

ABOUT THE 2dF INSTRUMENT

Designed and built by the Anglo-Australian Observatory, the 2dF is one of the world's most complex astronomical instruments, able to capture 400 spectra simultaneously. A robot arm positions up to 400 optical fibres on a field plate, each to within an accuracy of 20 micrometres. Light from up to 400 objects is collected and fed into two spectrographs for analysis. The expansion of the Universe shifts galaxy spectra to longer wavelengths. By measuring this "redshift" in a galaxy's spectrum, the galaxy's distance can be determined.

The 2dF Galaxy Redshift Survey used the 2dF to cover a total area of about 2,000 square degrees, selected from both northern and southern skies. It used about 250 nights observing time on the 4m-diameter Anglo-Australian Telescope, during 1995-2002. The 2dF Galaxy Redshift Survey is nearly ten times larger than the surveys that preceded it.

ABOUT THE 2dF GALAXY REDSHIFT SURVEY TEAM

Members of the team are based at the following institutions:

University of New South Wales, Anglo-Australian Observatory, Australian National University, California Institute of Technology, Johns Hopkins University, Liverpool John Moores University, University of Cambridge, University of Durham, University of Edinburgh, University of Leeds, University of Nottingham, University of Oxford, University of St Andrews.

CONTACTS

UNSW Faculty of Science media liaison:

Bob Beale - 0411 705 435



Professor Warrick Couch:

Office - 02-9385-4566
Mobile - 0413-011-371