Aussie galaxy survey to lead to 'new physics'

Dec 08, 2009
Time goes from top to bottom. The "bullseyes" show where there have been two sources of pressure waves in the early universe, the waves travelling outwards like the ripples on a pond. Galaxies prefer to grow at the centre and edge of the bullseye. Their preferred separation is the radius of the bullseye (the scale bar). Image: Sam Moorefield, Swinburne University.

(PhysOrg.com) -- Australian astronomers have released the first set of data from the first project to look at the effects of "dark energy" halfway back in the Universe's lifetime.

Called WiggleZ (“wiggles”), the project is being done with the Anglo-Australian Telescope in NSW and is led by Professor Michael Drinkwater of UQ's School of Mathematics and Physics.

Dark Energy is an unidentified component of the Universe that is causing the expansion of the Universe to speed up.

Determining its nature is one of the key problems of physics today, and will lead to a "new understanding of physics," Professor Drinkwater said.

WiggleZ will get a handle on Dark Energy by measuring “wiggles” in the distribution of distant galaxies.

Because light takes time to travel through the Universe, looking far out is equivalent to looking back in time, and WiggleZ is observing galaxies that existed when the Universe was half its present age.

“By observing the size of the pattern at different times in the Universe's history, we can track the history of the expansion of the Universe, and thus determine the effects of Dark Energy,” Professor Warrick Couch of Swinburne University, a member of the WiggleZ team, said.

The “wiggles” pattern in galaxies in today's Universe was discovered in 2004 by two teams, one of which had used the Anglo-Australian Telescope for its galaxy survey.

WiggleZ will measure the redshifts (distances) of 240,000 galaxies, allowing astronomers to create a 3D map of galaxies stretching over a thousand square degrees on the sky and look for a pattern in the way they are clustered on large scales.

These galaxies are about halfway back in the Universe's history (4 to 8 billion years ago, corresponding to redshifts of between 0.2 and 1).

WiggleZ started in 2006 and, when finished in 2010, will be the largest galaxy redshift survey made to that time in terms of the volume of space it covers at such remote distances in the .

More than a dozen ground-based Dark Energy projects are proposed or under way, and at least four space-based missions, each of the order of a billion dollars, are at the design concept stage.

While the exact nature of Dark Energy is still unknown, there are only a few candidates.

A favoured one is the energy of empty space itself. But it could also be that Einstein's general theory of relativity, our current theory of gravity, is wrong on large scales.

Another approach to tracking the effects of Dark Energy is to look at the brightness of distant supernovae (exploding stars), and compare them with the brightness predicted for that time in the Universe's history. This is how Dark Energy was discovered in the first place.

However, there are uncertainties associated with the supernova approach related to how close in brightness all the supernovae are.

“The galaxy clustering method also has uncertainties, but completely independent ones, so the two methods provide a powerful cross-check to each other,” Dr Sarah Brough, a WiggleZ team member at the Anglo-Australian Observatory in Sydney, said.

The first WiggleZ data release, of 100,000 , is published in association with a paper in Monthly Notices of the Royal Astronomical Society.

More information: Michael J. Drinkwater et al. “The WiggleZ Survey: Survey Design and First Data Release.” Accepted for publication in the Monthly Notices of the Royal Astronomical Society. On astro-ph at http://xxx.lanl.gov/abs/0911.4246

Provided by University of Queensland (news : web)

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User comments : 7

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degojoey
Dec 08, 2009
This comment has been removed by a moderator.
Alexa
4.7 / 5 (3) Dec 08, 2009
"Dark Energy" is technical term for group of observations, which are indeed real.
omatumr
1.6 / 5 (7) Dec 09, 2009
Too bad these Australian astronomers do not have time to study the real world.

They might even learn something that would benefit taxpayers, like the reason for cyclic changes in Earth's heat source - the Sun.

With kind regards,
Oliver K. Manuel
Former NASA PI for Apollo
ArcainOne
5 / 5 (6) Dec 09, 2009
It is amazing how tiny many peoples minds are in in their inability to comprehend even the slightest magnitude of anything beyond that of a mere mortal human life where only money makes any amount of importance and the city in the fraction of territory your government may own on this wondrous world we live on floating in an even more wondrous universe is all you are interested in knowing.

One day we will see these stars, and things that will make our tiny lives pale in comparison.
Simonsez
5 / 5 (2) Dec 09, 2009
Gah, is this site compatible with Internet Explorer? I have the hardest time giving star ratings to the correct people. 5 stars for ArcainOne and Alexa, not omatumr and Alexa.

While I understand the "economics" of the research, I will argue to my dying breath that such things are not just necessary but a benefit to all mankind. Who has never wondered for a better explanation of the existence we know as "all there is"? I love reading about new discoveries and experiments done that further our knowledge of the base universe that spawned our tiny, human life-supporting planet.
joekid
not rated yet Dec 09, 2009
I agree, or should I say I possibly agree with the view point the dark matter doesn't exist. It is possible that Dark matter is quantum an effect that no longer exists in our frame of reference. But once did. and time and distance out lived the particles. they could have changed in what ever way they could into matter that no longer is sufficient to affect us and the universe at the length we can stretch our senses with any accuracy. Einstein as Newton and Galileo before him were not wrong but incomplete in their laws and observations because of the weakness and inaccuracy of the equipment and information processed into usable form. Question: what do neutrinos become after they slow down?
RayCherry
5 / 5 (1) Dec 09, 2009
Oliver: you are making it obvious why you are 'Former' ...

I don't like anyone telling me that Dark Matter and Dark Energy may once have existed and can explain our current observations of the Universe, but if they really can justify their claims ... I'm listening.

Personally, I'm waiting to discover that the big bang was a local phenomenon in a much larger picture, but if we never get to see anything outside the CMB, I guess we'll have to work with what we can see, measure and ponder upon.

Ultimately, all these different projects put more technology are our disposal for a wide variety of perposes. More telescopes, more data, (more suns to observe help us understand the local star's behaviour), more knowledge and scientic enquiry for however much time we really have left.

Eventually they will listen, but screaming mutes their ambitions to learn.
magpies
not rated yet Dec 09, 2009
"A favoured one is the energy of empty space itself. But it could also be that Einstein's general theory of relativity, our current theory of gravity, is wrong on large scales."

Agree I do.

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