August 21, 2012

Debate Over Distribution Of Matter In The Universe Resolved By WiggleZ?

Brett Smith for - Your Universe Online

A debate that has been raging over the distribution of matter in the universe can finally be put to bed thanks to the WiggleZ Dark Matter survey that was conducted over 276 nights from August 2006 to January 2011.

The majority of physicists believe that the matter in the universe is distributed evenly on the largest scales and this outlook has fueled everything from Einstein´s equations to calculations that are the foundation for the Standard Model of particle physics.

But some scientists believe that on a larger scale, matter tends to act like mercury on a flat surface–clumping together in tiny pools that are separated by areas of empty space. To support this theory, these rogue physicists allude to the fact that stars come together to form galaxies, and galaxies huddle together to form clusters.

If this relatively recent alternative theory of the universe is correct, then almost every theoretical model on how particle physics works, including those involving dark matter, needs to be reassessed.

To settle this question, an international team of researchers turned to data culled from WiggleZ, the project dedicated to surveying the skies for evidence of dark matter – not the children´s musical group. Using state-of-the-art technology at the Anglo-Australian Telescope in Australia, the WiggleZ team is attempting to analyze the information gathered from surveying almost 240,000 galaxies, giving each one a precise distance from Earth and a precise location in space.

After pouring over the data, the team found that the galaxies were evenly distributed on scales larger than 350 million light years, according to their report published in Monthly Notices of the Royal Astronomical Society Journal.

“Our entire understanding of the Universe, even how we interpret the light we see from stars and galaxies, would be affected if the Universe were not even on large scales,” said study co-author Morag Scrimgeour a PhD student from the International Centre for Radio Astronomy Research (ICRAR) and The University of Western Australia in Perth.

“By looking at how the WiggleZ galaxies are distributed in space on scales up to 930 million light years, we find that they are very close to homogeneous, meaning there is no large-scale clustering. So we can say with a high degree of certainty that our picture of the large-scale Universe is correct.”

With the survey portion of the project over, the WiggleZ team continues to search for answers buried within the mountain of data they have collected. By tracking the ℠red shifts´ or infrared signatures of galaxies in the Australian night sky, they have already developed a vivid narrative describing how the matter in the universe is distributed.

“It seems that over billions of years,” a statement on group´s website reads,”as the universe grew larger and colder, and as stars and galaxies began to form, gravity pulled material towards and away from those early peaks and troughs of matter, sharpening the differences between them.”

“In this way, they became the template on which the modern universe is formed, with the hot spots becoming the seeds of super-clusters of galaxies and the cold spots giving rise to relative voids. “