New research led by Dr. Jörg Dietrich, from Ludwig-Maximilians-University (LMU) Munich, reports online on July 12, in the journal Nature, the detection of a dark-matter filament connecting two clusters of galaxies. "The presence of such filaments has been a key prediction of the theory of structure formation, which describes how structures on cosmological scales form after the Big Bang". Dr. Dietrich told The Munich Eye (TME).

The theory of structure formation predicts that such long strands of dark matter are found all across the Universe. Such structures are called filaments and galaxy clusters are found at the intersection of these filaments. "They are the nodes in this network, which is also called the cosmic web." The dark-matter filament was detected by its weak gravitational lensing signal. Gravitational lensing occurs when light headed toward Earth from a large distant object, such a galaxy, is bent as it approaches another large object.

"This significance of this paper is that it for the first time provides direct observational evidence for an important prediction of the theory of structure formation. Furthermore, we do not only see the filament in our data, we also can determine that its total mass and the ratio of hot gas to dark matter is in agreement with theoretical predictions," Dr. Dietrich told TME.

Article DOI: 10.1038/nature11224