Astrophysics - Cosmic Web of Dark Matter Host Massive Galaxy Clusters Spanning One Billion Light Years

For the first time astronomers at the University of Edinburghand University of British Columbia have mapped dark matter on the largest scale ever observed. Their findings reveal a Universe comprised of an intricate cosmic web of dark matter and galaxies that spans more than one billion light years, with the densest regions of the dark matter cosmic web hosting massive clusters of galaxies. 

An international team of 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.

Observations show that dark matter in the Universe is distributed as a network of gigantic dense (light) and empty (dark) regions, where the largest dense regions are about the size of several Earth moons on the sky. 

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.

"It is fascinating to be able to 'see' the dark matter using space-time distortion," said Ludovic Van Waerbeke, from the University of British Columbia. "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."

"By analysing light from the distant Universe, we can learn about what it has travelled through on its journey to reach us," said Dr Catherine Heymans, a Lecturer in the University of Edinburgh's School of Physics and Astronomy. "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,"observed Koen Kuijken, from Leiden University.

The image below shows that dark matter in the Universe is distributed as a network of gigantic dense (white) and empty (dark) regions, where the largest white regions are about the size of several Earth moons on the sky. Credit: Van Waerbeke, Heymans, and CFHTLens collaboration.

Image credits: Van Waerbeke, Heymans, and CFHTLens collaboration

Source: The Daily Galaxy - University of British Columbia