January 22, 2014

One of the filaments of matter that scientists think connects galaxies in a “cosmic web” has been imaged for first time. The images were captured by scientists from the University of California at Santa Cruz using the Keck telescope on the top of Mauna Kea in Hawaii. Many astronomers have long believed that the matter in the universe is not spread out evenly but is distributed in a weblike structure, or cosmic web. The filament imaged by the scientists was in a very large, bright, nebula that is about about 2 million light-years across. The scientists were able to see the filament because it was illuminated by a powerful black hole at the center of a galaxy located on the filament.

A filament in the cosmic web is illuminated by the light from a quaser in a computer simulation of one section of a nebula. (S. Cantalupo (UCSC); Joel Primack (UCSC); Anatoly Klypin (NMSU))

Computer simulations have shown how these filaments could form. However, finding direct evidence has not been so easy. The scientists were assisted by a type of super-massive black hole called a quasar. This type of black hole, like many huge black holes, sits the center of a galaxy. Unlike many other galaxy centers, however, a quasar shoots out two powerful jets of energy and matter. Like a flashlight, one of the jets lit up the filament leading up to the quasar, enabling the scientist to spot it and take an image.

The discovery has provided supporting evidence for the cosmic web theory. In addition, the finding is giving scientists much-needed clues about how the matter in the universe is distributed. Early information from the discovery suggests that there is much more matter in the filaments than many models have predicted. If correct, the evidence could force scientists to rethink the most widely accepted models of the structure of the universe.

Additional World Boook articles:

• Dark matter
• Interstellar medium
• The Formation of Galaxies and Other Structures