Space.com - 26 April 2010
Research illuminates the shape of dark matter's distributionElusive dark matter around clusters of galaxies often clumps into cigar shapes, new observations show.
The discovery could help scientists finally understand what makes up dark matter, which is the mystifying stuff thought to exist invisibly all around us. Dark matter, which could be more than five times more abundant than visible matter, is only detectable through its gravitational pull on regular material.
According to the new observations, the dark matter around many galaxy clusters is a flattened, cigar-like shape, rather than a rounded sphere.
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The fact that the dark matter seems to be flattened out into oblong shapes fits in with the so-called cold dark matter theory. Computer simulations based on this theory have predicted such shapes, but they have never before been verified to such an extent with so many large clusters.
The findings could shed light on the fundamental nature of this weird stuff, which scientists cannot detect directly. The observations support the possibility that dark matter is actually made of tiny particles called WIMPS (weakly-interacting massive particles) that exert a strong gravitational force, but otherwise don't interact with normal matter.
Astronomy.com - 26 April 2010
Research Illuminates the Shape of Dark Matter's DistributionA thorough examination of the shape of dark matter's distribution in the cosmos may open up a new way to explore the nature of this enigmatic matter.
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One approach to a solution is to make detailed measurements of the spatial distribution of dark matter and then compare the data to predictions drawn from theoretical models. Both aspects of this approach have their difficulties. How can scientists measure the distribution of dark matter? What are plausible assumptions to include in models of dark matter?
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In addition to the promise of using gravitational lensing for exploring the nature of dark matter, this research contributes to theoretical modeling of dark matter. Detailed comparisons of the team's findings with theoretical model predictions of the distribution of dark matter show that the observed degree of the flattening is in excellent agreement with theoretical expectations.
Theoretical predictions for dark matter distributions in clusters of galaxies are dependent on what kind of dark matter model is assumed. This research strongly supports the prevailing model, which begins with the assumption that dark matter consists of weakly interacting massive particles that are relics of the Big Bang.
Subaru Telescope Press Release - 26 April 2010
Dark Matter Halos Look a Bit Like a Football
Science NOW - 26 April 2010
Direct measurement of dark matter halo ellipticity from two-dimensional lensing shear maps of 25 massive clusters*
- Monthly Notices of the Royal Astronomical Society, (2010 April 23), DOI: 10.1111/j.1365-2966.2010.16622.x