Dark matter underpinnings of cosmic web found

THE skeleton of dark matter that undergirds the cosmic web of matter in the universe has been clearly detected for first time.

We know that matter in the cosmos forms a web, with galaxies and clusterslinked by filaments across mostly empty space. Filaments are made of normal matter and dark matter - the unseen stuff that makes up about 85 per cent of the universe's mass. Recent observations have seen the normal matter in such filaments.

Now Jörg Dietrich at the University Observatory in Munich, Germany, and his team have detected the dark matter component in a filament in a supercluster about 2.7 billion light years from us, called Abell 222/223.

The massive filament's gravity focuses the light travelling towards Earth from more distant background galaxies. The team used this light to calculate the filament's mass and shape. X-rays from the hot gas of normal matter in the vicinity showed that this matter lined up with the filament but made up only about 10 per cent of its mass. The rest must be dark matter (Nature, DOI: 10.1038/nature11224). This shows that the filament is "part of a network of dark matter that connects galaxy clusters throughout the universe", says Dietrich.

 source   NEW SCIENTIST