Images of faraway galaxies shed new light on dark matter

7th December 2016

Dark matter map of KiDS survey region (region G12)

Dark matter, the elusive material that accounts for much of the Universe, is less dense and more smoothly distributed throughout space than previously thought, according to a new study co-led by astronomers at the University of Edinburgh. The international team of scientists studied wide-area images of the distant universe, taken from the European Southern Observatory in Chile. They applied a technique based on the bending of light by gravity - known as weak gravitational lensing - to map out the distribution of dark matter in the Universe today. Their study represents the largest area of the sky to be mapped using this technique to date.

The new results contradict previous predictions from a survey of the far-off universe, representing a point in time soon after the Big Bang, imaged by the European Space Agency's Planck satellite. This previous study used a theoretical model to project how the Universe should appear today. The disagreement between this prediction and the latest direct measurements suggests that scientists' understanding of the evolving modern day Universe is incomplete and needs more research.

The latest study, published in Monthly Notices of the Royal Astronomical Society, was carried out by a team jointly led by the University of Edinburgh, the Argelander Institute for Astronomy in Germany, Leiden University in the Netherlands and Swinburne University of Technology, Australia in an ongoing project called the Kilo Degree Survey, or KiDS. It was supported by the European Research Council.

Dr Hendrik Hildebrandt of the Argelander Institute for Astronomy in Germany, said: "Our findings will help to refine our theoretical model for how the Universe has grown since its inception, improving our understanding of the modern day Universe.”

Dr Massimo Viola of Leiden University in the Netherlands, said: "This latest result indicates that the cosmic web dark matter, which accounts for about one-quarter of the Universe, is less clumpy than we previously believed.”

Professor Catherine Heymans of the University of Edinburgh's School of Physics and Astronomy, said: "Unravelling what has happened since the Big Bang is a complex challenge, but by continuing to study the distant skies, we can build a picture of how our modern Universe has evolved.”


Professor Catherine Heymans
Institute for Astronomy,
University of Edinburgh,
Blackford Hill,
EH9 3HJ, UK.

Related Links:

ESO Press release and images

Open Access Research Paper

Dark matter map of KiDS survey region (region G12)

Dark matter map of KiDS survey region (region G12)

This map of dark matter in the Universe was obtained from data from the KiDS survey, using the VLT Survey Telescope at ESO’s Paranal Observatory in Chile. It reveals an expansive web of dense (light) and empty (dark) regions. This image is one out of five patches of the sky observed by KiDS. Here the invisible dark matter is seen rendered in pink, covering an area of sky around 420 times the size of the full moon. This image reconstruction was made by analysing the light collected from over three million distant galaxies more than 6 billion light-years away. The observed galaxy images were warped by the gravitational pull of dark matter as the light travelled through the Universe.