Astronomers have for the first time mapped the largest scale of dark matter ever observed. Their findings reveal a Universe comprising an intricate cosmic web of dark matter and galaxies spanning more than one billion light years.
An international team of researchers lead by Associate Professor Ludovic Van Waerbeke of the University of British Columbia and Dr Catherine Heymans of the University of Edinburgh, Scotland, 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 (CFHTLenS), uses data from the Canada-France-Hawaii Telescope Legacy Survey.
This accumulated images over five years using the wide field imaging camera MegaCam, a 1 degree by 1 degree field-of-view, 340 Megapixel camera on the CFHT in Hawaii.
Galaxies included in the survey are typically six billion light years away. The light captured by the 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.
“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,” said Professor Van Waerbeke.
Dr Heymans said: “By analysing light from the distant Universe, we can learn about what it has travelled through on its journey to reach us. We hope that by mapping more dark matter than has been studied before, we are a step closer to understanding this material and its relationship with the galaxies in our Universe.”
“Over the next three years we will image more than 10 times the area mapped by CFHTLenS, bringing us ever closer to our goal of understanding the mysterious dark side of the Universe,” added Professor Koen Kuijken, from Leiden University.
The results were presented to the American Astronomical Society meeting in Austin, Texas.