Here are galaxy clusters Abell 222 and Abell 223 with the dark matter filament connecting them. (Photo : Jörg Dietrich)
Everyone is talking about the recent Higgs boson announcement by the scientists at CERN, but another significant scientific discovery was revealed this week as well. In a study published online in the journal Nature on Wednesday, scientists show that they have successfully found the first dark matter filament.
Dark matter does not emit or absorb light or electromagnetic radiation at a detectable level. This essentially makes it invisible. It is believed, however, that dark matter constitutes almost 85 percent of the mass in the entire universe. Dark matter filaments are strands of dark matter that usually connect galaxy clusters and help give the universe the structure we observe today.
To detect dark matter, scientists usually have to look for the gravitational pull that it exerts on surrounding visible objects like stars or galaxies and even light. Concentrations of dark matter in galaxy clusters are easier to detect because there is so much of it (hence all the galaxies clustering together due to its pull) but dark matter filaments are harder to detect because they are so thin and there is little light for them to bend.
The scientists found a dark matter filament 2.7 billion light years away connecting galaxy clusters Abell 222 and Abell 223 .
"This is the first time [a dark matter filament] has been convincingly detected from its gravitational lensing effect," said astronomer Jörg Dietrich of the University Observatory Munich, in Germany. "It's a resounding confirmation of the standard theory of structure formation of the universe. And it's a confirmation people didn't think was possible at this point."
It was believed that more advanced telescopes would be needed, but the team used gravitational lensing to detect the filament.
"The standard wisdom is that the gravitational lensing of filaments is too weak to be detected with current telescopes," Dietrich told SPACE.com. "Only when we realized this system has such a peculiar geometry did we realize we have a chance."