The University of Nottingham

Eight billion years ago rays of light from distant galaxies began their long journey to Earth. On September 12 2012 that ancient starlight found its way to a mountaintop in Chile where the newly-constructed Dark Energy Camera, the most powerful sky-mapping machine ever created, captured and recorded it for the first time.

The University of Nottingham is one of 23 institutions from across the world involved in the Dark Energy Survey (DES). A team of three scientists in the School of Physics and Astronomy are taking leading roles in the survey which is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision.

The Dark Energy Camera is the first device specifically designed to search for dark energy. It is the most powerful survey instrument of its kind, able to see light from over 100,000 galaxies up to eight billion light years away in each snapshot. The starlight it has captured may hold within it the answer to one of the biggest mysteries in physics — why the expansion of the universe is speeding up? The first image captured by the Dark Energy Camera can be viewed here.

Scientists on the Dark Energy Survey (DES) collaboration announced this week that the Dark Energy Camera, the product of eight years of planning and construction by scientists, engineers, and technicians on three continents, has achieved first light. The first pictures of the southern sky were taken by the 570-megapixel camera on 12 September.

The University of Nottingham is part of DES:UK — a consortium of six universities including University College London, University of Portsmouth, University of Cambridge, The University of Edinburgh and University of Sussex. As core members of this major international collaboration, DES:UK will be able to exploit the survey data and results as soon as they become available.

Nottingham’s dark energy team

Over 120 scientists in the Dark Energy Survey collaboration will use the new camera to carry out the largest galaxy survey ever undertaken, and will use that data to carry out four probes of dark energy, studying galaxy clusters, supernovae, the large-scale clumping of galaxies, and weak gravitational lensing. This will be the first time all four of these methods will be possible in a single experiment, and scientists from The University of Nottingham are closely involved in many aspects of the work, as well as other projects for which these data will provide a unique resource.

Professor Alfonso Aragón-Salamanca is taking a leading role in the planning and implementation of the future spectroscopic follow-up surveys and will lead the study of the effect of the environment on the properties and evolution of galaxies. Dr Meghan Gray is providing her expertise in understanding galaxy clusters and gravitational lensing to the DES Cluster Working Group. On the more theoretical side, Professor Ed Copeland will contribute his skills to the interpretation of the observed properties of dark energy and its links with fundamental particle physics.

Professor Aragón-Salamanca said: “The first images obtained with any new camera are always beautiful to see, but in this case there is the extra thrill that we may be taking the pictures that unravel some of the key mysteries of the Universe, and we are excited that The University of Nottingham is playing its part in solving these puzzles.”

Exploration beyond the cosmic frontier

The 570-megapixel Dark Energy Camera is the product of eight years of planning and construction by scientists, engineers, and technicians on three continents. A single camera image captures an area 20 times the size of the moon as seen from Earth. With this device, roughly the size of a phone booth, astronomers and physicists will probe the mystery of dark energy — the force they believe is causing the universe to expand faster and faster.

James Siegrist, America’s Department of Energy’s Associate Director of Science for High Energy Physics, said: “The achievement of first light through the Dark Energy Camera begins a significant new era in our exploration of the cosmic frontier. The results of this survey will bring us closer to understanding the mystery of dark energy, and what it means for the universe.”

Brenna Flaugher, project manager and scientist at Fermilab, America’s premier national laboratory for particle physics research, said: “The Dark Energy Survey will help us understand why the expansion of the universe is accelerating, rather than slowing due to gravity. It is extremely satisfying to see the efforts of all the people involved in this project finally come together.”

Answering the outstanding questions of our time

The camera’s array of 62 charged-coupled devices have an unprecedented sensitivity to very red light, and along with the Blanco telescope’s large light-gathering mirror (which spans 13 feet across), will allow scientists from around the world to pursue investigations ranging from studies of asteroids in our own Solar System to the understanding of the origins and the fate of the universe.

Chris Smith, director of the Cerro-Tololo Inter-American Observatory, said: “We’re very excited to bring the Dark Energy Camera online and make it available for the astronomical community. With it, we provide astronomers from all over the world a powerful new tool to explore the outstanding questions of our time, perhaps the most pressing of which is the nature of Dark Energy.”

The Dark Energy Survey is expected to begin in December, after the camera is fully tested, and will take advantage of the excellent atmospheric conditions in the Chilean Andes to deliver pictures with the sharpest resolution seen in such a wide-field astronomy survey.

Over five years, the survey will create detailed colour images of one-eighth of the sky, or 5,000 square degrees, to discover and measure 300 million galaxies, 100,000 galaxy clusters, and 4,000 supernovae.

The Dark Energy Survey is supported by funding from the U.S. Department of Energy; the National Science Foundation; funding agencies in the United Kingdom, Spain, Brazil, Germany, and Switzerland; and the participating DES institutions.

More information about the Dark Energy Survey, including the list of participating institutions, is available at the project website: www.darkenergysurvey.org