Eight billion years ago, rays of light from distant galaxies began their long journey to Earth. On 12 September, 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.
That light may hold within it the answer to one of the biggest mysteries in physics – why the expansion of the universe is speeding up. Although dark energy appears to account for about 75% of the energy-mass content of the universe, scientists have no real idea what it is.
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.
UK astronomers are key players in the DES collaboration, which is led by Fermilab in the US. The UK consortium comprises UCL (University College London), Portsmouth, Cambridge, Edinburgh, Sussex and Nottingham. The construction of the DES Camera was partially supported by UK’s Science and Technology Facilities Council (STFC).
Professor Ofer Lahav, from UCL, who heads the DES:UK Consortium and the DES science committee commented: “The achievement of first light through the Dark Energy Camera brings us a step closer to understanding dark energy, one of the biggest mysteries in the whole of physics. The deep observations with the DES camera will tell us why the universe is speeding up and if a major shift is required in our understanding of the universe.”
The Dark Energy Camera, which is roughly the size of a phone booth, is the most powerful survey instrument of its kind, able to see light from over 100,000 galaxies up to 8 billion light years away in each snapshot. 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.
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.
Professor Will Percival, University of Portsmouth, who co-coordinates the galaxy clustering of DES commented: “This will be the largest galaxy survey of its kind, and the galaxy shapes and positions will tell us a great deal about the nature of the physical process that we call Dark Energy, but do not currently understand.”
Professor Richard McMahon, University of Cambridge, added: “The construction of a 3-dimensional map of the galaxies just based on their positions and optical colours is extremely challenging and will require sophisticated computational and statistical techniques. The addition of galaxy near infrared colours from another UK led sky mapping survey, the VISTA Hemisphere Survey, will greatly improve the accuracy of the map”.
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.
In addition to STFC’s contribution, DES is supported by funding from the U.S. Department of Energy; the National Science Foundation; and funding agencies in Spain, Brazil, Germany, and Switzerland; and the participating DES institutions.
- Jake Gilmore
STFC Media Manager
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- Clare Ryan
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- Kate Daniell
University of Portsmouth
Tel: +44 (0)2392843743
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- Science Contacts:
Professor Ofer Lahav, UCL, Chair of DES:UK Consortium and the DES Science Committee, mobile: 44-77388-48597
- Professor Richard McMahon, University of Cambridge, DES Quasar science working group and PI of VISTA Hemisphere Survey, tel: 01223-337548; mobile: 07885-409019
- Professor Will Percival, University of Portsmouth, DES large-scale structure working group co-coordinator, tel: 02392843107, mobile: 07974564017
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