Illinois contributes camera components, data intensive computing, and scientific analyses
Champaign—Eight billion years ago, rays of light from distant galaxies began their long journey to Earth. Now 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 the answer to one of the biggest mysteries in physics–why the expansion of the universe is speeding up.
The 570-megapixel camera, roughly the size of a phone booth, is the product of eight years of planning and construction by scientists, engineers, and technicians on three continents. Much of the camera’s data acquisition electronics and control software were built in Urbana by a team of Illinois particle physicists led by Professor Jon Thaler.
With this device, scientists in the international Dark Energy Survey (DES) collaboration will undertake the largest galaxy survey ever attempted and will use that data—to be stored and processed at Illinois’ National Center for Supercomputing Applications (NCSA)—to carry out four probes of dark energy: studying galaxy clusters, supernovas, the large-scale clumping of galaxies, and weak gravitational lensing. This is the first time all four methods will be possible in a single experiment.
Zoomed-in image from the Dark Energy Camera of the barred spiral galaxy NGC 1365, in the Fornax cluster of galaxies, which lies about 60 million light years from Earth. Credit: Dark Energy Survey Collaboration.
“The combined analyses of the scientists in the DES collaboration are expected to contribute significantly to our understanding of the properties of dark energy and dark matter,” said Thaler. “The Illinois physics team will look at supernovas to chart the expansion of the universe over time, and at gravitational lensing to determine the history of the formation of structure (galaxies and galaxy clusters).
“Gravitational lensing is similar to optical lensing: just like glass, gravity also bends light. Light from distant stars and galaxies bends on its way to Earth as it is pulled by the gravity of objects that it passes—this bending distorts the shapes of distant galaxies. Normal matter and dark matter both have this effect, so measuring this distortion tells us how the dark matter contributes to galactic structure,” he said.
Over five years, the survey will create detailed color 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 supernovas.
“Hidden within the galaxy cluster distribution are clues to the nature of the universe we live in,” said Dr. Robert Gruendl of the Illinois Astronomy Department.
Gruendl, together with Don Petravick of NCSA and other collaborators have developed and will operate a data management framework for processing, calibrating, and archiving the massive amounts of data—petabytes over the lifetime of the survey—that will be collected for the DES. This system relies on the iForge cluster and a 100-terabyte Oracle database at NCSA and also uses high-performance computing resources provided by the National Science Foundation’s XSEDE
(Extreme Science and Engineering Discovery Environment) project.
Full Dark Energy Camera image of the Fornax cluster of galaxies, which lies about 60 million light years from Earth. The center of the cluster is the clump of galaxies in the upper portion of the image. The prominent galaxy in the lower right of the image is the barred spiral galaxy NGC 1365. Credit: Dark Energy Survey Collaboration.
"NCSA provides the networking, computing, and archiving capabilities and sophisticated tools that this type of data-intensive science requires,” said NCSA’s Don Petravick, who leads the data management project. "This allows astronomers and physicists to focus on analysis of science-ready data, rather than spending their time on preliminary processing or technical issues."
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 a wide-field astronomy survey.
The DES 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.