Dark Matter....Images

Dark matter images reveal widest view of dark mystery

The survey dwarfs the previous largest map, shown at centre alongside the moon for comparison of size in the sky

Researchers have released the biggest images yet detailing dark matter, the mysterious substance that makes up three-quarters of the Universe's mass. Each image, a billion light-years across, shows vast dark matter clumps and voids scattered through the cosmos. The team from the Canada-France Hawaii Telescope inferred the dark matter's existence by the way it bends light.

The images were presented at the 219th meeting of the American Astronomical Society in Austin,Texas. The four images were taken at four different seasons of the year, each capturing a swath of the sky about as large as a palm held at arm's length. They are a big step forward in understanding both dark matter itself, and the means by which dark matter influences the way normal matter clumps into the galaxies we see in the night skies. Together, they represent the images of more than 10 million galaxies, whose light gives the only hints of the large-scale structure of dark matter.

Dark energy and dark matter mysteries

• Gravity acting across vast distances does not seem to explain what astronomers see
• Galaxies, for example, should fly apart; some other mass must be there holding them together
• Astrophysicists have thus postulated "dark matter" - invisible to us but clearly acting on galactic scales
• At the greatest distances, the Universe's expansion is accelerating
• Thus we have also "dark energy" which acts to drive the expansion, in opposition to gravity
• The current theory holds that 73% of the Universe is dark energy, 23% is dark matter, and just 4% the kind of matter we know well

Light coming toward us from a distanct galaxy is bent by the gravity of a lump of matter in the middle.

Einstein's theory of general relativity tells us that mass bends space and time, so when light comes toward us through the Universe, if it passes some dark matter, its light gets bent and the image we see gets bent and distorted.

The survey is some 100 times larger than the previous largest map of the web of dark matter, gathered by the Hubble telescope's Cosmic Evolution Survey, or Cosmos. In the new image, the full-scale distribution of vast clumps of dark matter can be seen around galaxy clusters, connected by wispy filaments of dark matter and trailing off to enormous voids where no matter exists. Thankfully for theoretical astrophysicists, these images line up neatly with theory.

 Theories of dark matter say that it should form a giant intricate cosmic web and that's exactly what we see in this data, a cosmic web that's housing all the galaxies that we can see.