Press Release

Gift of galaxies will fuel new findings

By SpaceRef Editor
June 5, 2001
Filed under ,

Redshift data and spectra from the first 100,000 galaxies measured by the
2dF (Two-degree Field) Galaxy Redshift Survey will be released to the
world astronomical community on June 30. Thirty-two researchers from 13
institutions (listed below) have been carrying out the survey with the
Anglo-Australian Telescope near Coonabarabran in eastern Australia. They
have now netted more than 175,000 redshifts and will reach the survey
target of 250,000 by the end of 2001. Redshift data can be converted to
positions in space and so the survey has created the most comprehensive
three-dimensional map of the local Universe yet made.

As well as providing by far the largest available set of galaxy spectra for
mapping the Universe, the 2dFGRS database is a goldmine of interesting and
unusual objects.

“The 2dF dataset is a free gift of 100,000 redshifts to astronomers
world-wide. They can apply it immediately to improving our understanding
of galaxy evolution and the structure of the Universe,” said 2dF survey
team co-leader Dr Matthew Colless of the Australian National University.

“For many rare types of objects, we need to have large samples before we
can understand the objects’ properties and how they are related to their
environments,” he said.

“For instance, radio telescopes are extremely good at detecting extremely
powerful, ‘active’ galaxies in the very distant universe. But to understand
how these galaxies evolve over time, we need also a large sample of such
galaxies nearby. This can only be achieved with an optical telescope,” Dr
Colless said. “Cross-matching the 2dF survey data with large-area radio
surveys will give a sample of up to 4,000 radio-emitting galaxies in the
local Universe.”

A key finding from the data, posted at
on May 15, is the first firm evidence that the irregularities in the cosmic
microwave background are still imprinted on the distribution of galaxies in
today’s Universe. The large sample of galaxies generated by the 2dF survey
allowed the researchers to measure the characteristics of the galaxy
distribution with very small random errors. “These subtle over-densities in
the galaxy distribution range in size from about 300 million to 1.5 billion
light-years,” said team co-leader Prof. John Peacock of the University of

The same study also found that ‘normal’ (baryonic) matter makes up only 15%
of the Universe’s total matter — the rest being the unidentified ‘dark
matter’. And total matter is only 35% of the Universe’s contents, according
to another 2dF finding in ‘Nature’ on March 8. (The rest is believed to be
‘dark energy’.)

The 2dF dataset will also be used to test theories of cosmological inflation,
the extremely rapid growth of the Universe just after the Big Bang.

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 survey covers a total area of about 2,000 square degrees, selected
from both northern and southern skies.


  • Anglo-Australian Observatory — Joss Bland-Hawthorn, Terry Bridges, Russell
  • Cannon, Ian Lewis
  • Australian National University — Matthew Colless*, Carole Jackson, Bruce
  • California Institute of Technology — Richard Ellis, Keith Taylor
  • Johns Hopkins University — Ivan Baldry, Karl Glazebrook
  • Liverpool John Moores University — Chris Collins
  • University of Cambridge — George Efstathiou, Ofer Lahav, Darren Madgwick
  • University of Durham — Carlton Baugh, Shaun Cole, Carlos Frenk, Peder
  • University of Edinburgh — John Peacock*, Will Percival, Will Sutherland
  • University of Leeds — Stuart Lumsden
  • University of New South Wales — Warrick Couch, Kathryn Deeley, Roberto de Propris
  • University of Nottingham — Edward Hawkins, Steve Maddox*
  • University of Oxford — Gavin Dalton, Mark Seaborne
  • University of St Andrews — Nicholas Cross, Simon Driver

* Team leaders

Email addresses are given at


The 2dF Galaxy Redshift Survey has been made possible by the dedicated efforts
of the staff of the Anglo-Australian Observatory, both in creating the 2dF
instrument and in supporting it on the telescope.


The 2dF Galaxy Redshift Survey data will be available after June 30, 2001 from



Dr Matthew Colless, Australian National University


Professor John Peacock, Royal Observatory Edinburgh


Professor Richard Ellis, California Institute of Technology



Helen Sim, Anglo-Australian Observatory, Sydney, Australia

SpaceRef staff editor.