Waterloo researchers capture first ever image of dark matter web connecting galaxies

Dark Matter is a mysterious substance that has got its name because scientists can observe the gravitational effects it has on stars and galaxies in the universe, but have been unable to directly observe it. Researchers from the University of Waterloo have pieced together the first composite image of dark matter, proving that the material exists in the void between galaxies. The images confirm that the dark matter stretches between galaxies, and ties them together in a cosmic web.

Mike Hudson, a professor of astronomy at the University of Waterloo said, “For decades, researchers have been predicting the existence of dark-matter filaments between galaxies that act like a web-like superstructure connecting galaxies together. This image moves us beyond predictions to something we can see and measure. "

Dark matter is believed to make up 25 percent of the known universe. However the material does not reflect or absorb light, does not shine, and has historically been undetectable. The researchers used a phenomenon known as gravitational lensing, where the light from distant celestial objects are warped by massive bodies on their way to Earth, usually other galaxies.

The researchers combined lensing images from over 23,000 pairs of galaxies located 4.5 billion light years away to create the composite image. The images were collected using a sky survey that took place over a period of many years. The results showed that the filaments of dark matter were strongest between galaxies that were less than forty million light years apart.

The research paper has been published in the  Monthly Notices of the Royal Astronomical Society .