Researchers Find Dark Matter Blob That Could Rewrite Understanding of Galaxies: Scientists Baffled by Dark Matter Mystery

Article excerpt

VANCOUVER - Roughly 2.4 billion light years from Earth, a massive blob of a mysterious, invisible substance known as dark matter is threatening to rewrite how scientists on this planet understand galaxies.

Dark matter -- which accounts for more than 80 per cent of all matter in the universe -- has been described as the glue that holds galaxies together through gravity.

It's invisible, but it surrounds galaxies and larger clusters of galaxies. To detect it, scientists study how the gravity from dark matter bends and distorts light passing through it.

Currently, scientists believe that dark matter doesn't have much effect on the surrounding environment other than through its gravitational pull. In other words, if two galaxies collide, the dark matter from one galaxy would pass right through the dark matter from the other, as it if didn't exist.

But researchers in Canada and the United States have detected what they are describing as a "dark core" -- a large clump of dark matter that appears to have collided and stuck together, even as the galaxies the dark matter was attached to continued to move on.

"It challenges conventional understanding of dark matter and how dark matter should behave," said Arif Babul of the University of Victoria.

"It's potentially suggesting dark matter has a bit of stickiness to it that we hadn't expected before, and that stickiness could then change how galaxies like our own Milky Way come together."

The scientists first made the discovery in 2007 using a telescope based in Hawaii.

They were looking at Abell 520, a collection of several galaxy clusters that are colliding into one another other at high speed, which has been described as a "cosmic train wreck."

It was in the centre of Abell 520 that they noticed a clump of dark matter that appeared to be left over from the colliding galaxy clusters, even though prevailing wisdom about dark matter suggested that should not happen. …