Stretches 270 million light years into space

Mar 17, 2008 15:59 GMT  ·  By

If it were visible from the Earth with the naked eye, it would appear as a structure eight times bigger than the apparent size of the Moon! Measuring more than 270 million light-years across, the newly discovered cloud is the largest structure of dark matter ever observed. The discovery was made by an astronomer from the University of British Columbia, namely assistant professor in the Department of Physics and Astronomy Ludovic Van Waerbeke.

"The results are a major leap forward since the presence of a cosmic dark matter web that extends over such large distances have never been observed before," said Van Waerbeke. Through a technique called "weak gravitational lensing" and the help of the world's biggest digital camera, the team was able to obtain an image of the sky, relatively similar to that of an X-ray of the skeleton of a living being.

Considering the fact that dark matter is thought to be responsible for about 75 percent of the total mass of the universe, one may say that we are finally starting to make some progress in understanding the history and evolution of the cosmos. "Such a tool will also enable us to glimpse a little more of the nature of dark matter," said Van Waerbeke.

Similar to traditional gravitational lensing effects, dark matter webs also bend light coming from background galaxies as it travels towards the Earth; thus, measuring these slight distortions, the team was eventually able to reveal a map of the dark matter structure. The technique took a couple of years to be perfected and involved 19 researchers from 11 institutions, amongst which the Institut d'Astrophysique de Paris, the Universite Pierre and Marie Curie and the University of Victoria.

The study is part of the Canada-France-Hawaii Telescope (CFHT) Legacy Survey, CFHT being a non-profit organization, operating the 3.6 meter telescope located on Mauna Kea. Previously, Van Waerbeke and his team was credited for creating the highest resolution map of a dark matter cloud.