Hunting for dark energy with the WiggleZ

Box 3 | Team, task, technology

The WiggleZ team draws together researchers from a number of universities in Australia as well as from the Anglo-Australian Telescope (where the observations are being made) and from the California Institute of Technology (Caltech). Caltech operates the GALEX space-based telescope which helped to choose the target galaxies for the WiggleZ team.

The WiggleZ project builds on the achievements of the earlier Two Degree Field (2dF) Galaxy Redshift Survey. This survey revealed the imprint of sound waves of the early universe in the way galaxies are now laid out across the universe in a ripple-like pattern. The WiggleZ team was formed in 2004 with the challenge of making the first precision measurements of this evidence for baryonic wiggles at high redshiftBy comparing the observed pattern of galaxies now with the patterns in the early universe (from the cosmic microwave background) a measurement of dark energy will be made that is independent of other studies.

When complete in 2010, the WiggleZ survey will have mapped 200,000 chosen galaxies, spread across an area of the sky totalling 1000 square degrees. This enormous task will require around 200 nights of observation at the Anglo-Australian Telescope.

The key tool of the WiggleZ team is the AAOmega spectrograph. This is one of the world’s most complex astronomical instruments. Within the field of view of the telescope, a robot arm positions up to 400 individual optic fibres, each one aligned precisely to collect light from just one galaxy. Analysis of the light from each galaxy reveals its redshift, which provides its speed and (given the Hubble constant) how far away it is.

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Page updated January 2010.