- An international team of scientists made the discovery using the Hubble Space Telescope to view the simultaneous collision of four distant galaxies at the centre of a galaxy cluster 1.3 billion light years away from Earth. The researchers said one dark matter clump appeared to be lagging behind the galaxy it surrounds.
- They said the clump was currently offset from its galaxy by 5,000 light years (50,000 million million km) - a distance it would take NASA's Voyager spacecraft 90 million years to travel. Such an offset is predicted during collisions if dark matter interacts, even very slightly, with forces other than gravity.
- In the latest study, the researchers were able to "see" the dark matter clump because of the distorting effect its mass has on the light from background galaxies - a technique called gravitational lensing. The researchers added that their finding potentially rules out the standard theory of Cold Dark Matter, where dark matter interacts only with gravity.
Potential signs of 'interacting' dark matter suggest it is not completely dark after all
4. 15. 15 by Ethan Fox