Astronomers have finally managed to find proof of decades old theory that states that two galaxies are connected through a dark matter bridge – a web-like superstructure.
Researchers at University of Waterloo in Canada have managed to create a composite image that shown in false colour the dark matter cosmic web that connects two galaxies. This particular form of a dark matter bridge has been predicted for decades, but it is only now that scientists have been able to observe such a superstructure.
Astronomers and physicists have long proposed that dark matter makes up 25 per cent of the known universe. The peculiarity of the dark matter is that it neither shines nor reflects light and this effectively makes it undetectable, except through gravity.
Scientists behind the new discovery say that their composite image takes us towards reality and farther away from predictions to a point where we are able to see and measure such intergalactic dark matter bridges.
Astronomers used a technique called weak gravitational lensing, an effect that causes the images of distant galaxies to warp slightly under the influence of an unseen mass such as a planet, a black hole, or in this case, dark matter. The effect was measured in images from a multi-year sky survey at the Canada-France-Hawaii Telescope.
Scientists then combined lensing images from more than 23,000 galaxy pairs located 4.5 billion light-years away to create a composite image or map that shows the presence of dark matter between the two galaxies. Results show the dark matter filament bridge is strongest between systems less than 40 million light years apart.
“By using this technique, we’re not only able to see that these dark matter filaments in the universe exist, we’re able to see the extent to which these filaments connect galaxies together,” one of the astronomers involved with the study says.