N. 1 - 18 gen 2012
International info a cura di Cecilia Migali
University of British Columbia and University of Edinburgh astronomers have mapped dark matter on the largest scale ever observed, according to results released at the American Astronomical Society meeting in Austin, Texas. The findings, presented by Dr Catherine Heymans of the University of Edinburgh, Scotland, and Associate Professor Ludovic Van Waerbeke of UBC, reveal a Universe comprised of an intricate cosmic web of dark matter and galaxies that spans more than one billion light years.
The researchers achieved their results by analysing images of about 10 million galaxies in four different regions of the sky. They studied the distortion of the light emitted from these galaxies, which is bent as it passes massive clumps of dark matter during its journey to Earth.
Their project, known as the Canada-France-Hawaii Telescope Lensing Survey, uses data from the Canada-France-Hawaii Telescope Legacy Survey. Galaxies included in the survey are typically six billion light years away. The light captured by the telescope images used in the study was emitted when the Universe was six billion years old - roughly half the age it is today.
The team's result has been suspected for a long time from studies based on computer simulations, but was difficult to verify owing to the invisible nature of dark matter. This is the first direct glimpse at dark matter on large scales showing the cosmic web in all directions.
Professor Ludovic Van Waerbeke, from the University of British Columbia, said: "It is fascinating to be able to 'see' the dark matter using space-time distortion. It gives us privileged access to this mysterious mass in the Universe which cannot be observed otherwise. Knowing how dark matter is distributed is the very first step towards understanding its nature and how it fits within our current knowledge of physics."