OTTAWA, April 14 (Xinhua) -- A composite image of a dark matter web, which is believed to connect galaxies, was captured for the first time by Canadian researchers.
The false color image, published in Monthly Notices of the Royal Astronomical Society on Wednesday, shows two galaxies, in white, connected by a bridge of dark matter in the red region. The two galaxies are about 40 light years apart.
"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, professor of astronomy at the University of Waterloo, in a statement on the university website.
"This image moves us beyond predictions to something we can see and measure," he said in the statement.
Dark matter, which makes up an estimated 25 percent of the universe, can not be directly observed because it does not shine, reflect or interact with light, but its existence and properties are inferred from its gravitational effects such as the motions of visible matter.
By using weak gravitational lensing, Hudson and his co-author Seth Epps measured the effect that dark matter has on light and created a composite image showing the presence of the mysterious substance.
The technique not only enables us to see the existence of dark-matter filaments in the universe, but to observe the extent to which these filaments connect galaxies, Epps said.
