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UW researchers capture image of dark matter web connecting galaxies

Last Updated Apr 18, 2017 at 9:42 am EDT

Dark matter filaments (shown in red) bridge the space between galaxies (shown in white) on this false colour map. (Photo from the University of Waterloo)

By Martin Bauman

Researchers at the University of Waterloo have done what no others have been able to do before.

The findings show the universe’s galaxies are more connected than one might think.

A team at UW managed to capture the first composite image of dark matter connecting galaxies, offering proof for theories that galaxies across the universe are connected by a cosmic web.

“We knew that there was dark matter around galaxies, but what we haven’t seen before is the bridge, the cosmic web, these filaments of dark matter that stretch between galaxies,” says Mike Hudson, a professor of astronomy at UW.

“This is something that had been predicted by some theories of dark matter, and some models of how clusters of galaxies grow as time progresses within the universe.”

Until this composite image, dark matter has been notoriously hard to detect, except through gravity — it doesn’t shine, absorb, or reflect light. Hudson and fellow researcher Seth Epps, a former master’s student at UW, used a technique called weak gravitational lensing to make the discover.

“Any kind of matter that has gravity will distort the images of background galaxies, and if we measure this distortion, we can turn that measurement of distortion into a map of dark matter — so that’s what we did, by scanning a large area of the sky,” says Hudson.

The findings mark the culmination of research which started in the early 2000s.

“I just think it’s pretty amazing that you can take a picture of dark matter, effectively,” beams Hudson.