The first composite picture of a dark matter bridge has been captured by scientists. The dark matter bridge is a web-like superstructure that connects galaxies together. Astronomers have been predicting it for decades.
The image combines several individual images and has confirmed the predictions that galaxies in the universe are tied together through a cosmic web connected by dark matter. This discovery had been unobservable until now.
The mysterious substance dark matter comprises around 25 per cent of the universe. It does not absorb or reflect light, nor shines because of which it has traditionally been largely undetectable, except through gravity.
“For decades, researchers have been predicting the existence of dark-matter filaments between galaxies that act like a web-like superstructure connecting galaxies together,” said Mike Hudson, a professor of astronomy at the University of Waterloo in Canada.
“This image moves us beyond predictions to something we can see and measure,” said Hudson.
A technique called weak gravitational lensing was used by Hudson and Seth Epps, researcher at the University of Waterloo. This technique causes the pictures 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.
Pictures from a multi-year sky survey at the Canada-France-Hawaii Telescope were used to measure the effect.
Lensing images from more than 23,000 galaxy pairs located 4.5 billion light-years away were combined in order to produce a composite image or map, showing 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,” said Epps.
The research was published in the journal Royal Astronomical Society.