World's most powerful digital camera records first images in hunt for dark energy

Siv Schwink and Tricia Barker
9/17/2012

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.
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.
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.

 

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Imagine planting a single seed and, with great precision, being able to predict the exact height of the tree that grows from it. Now imagine traveling to the future and snapping photographic proof that you were right.

If you think of the seed as the early universe, and the tree as the universe the way it looks now, you have an idea of what the Dark Energy Survey (DES) collaboration has just done. In a presentation today at the American Physical Society Division of Particles and Fields meeting at the U.S. Department of Energy’s (DOE) Fermi National Accelerator Laboratory, DES scientists will unveil the most accurate measurement ever made of the present large-scale structure of the universe.

These measurements of the amount and “clumpiness” (or distribution) of dark matter in the present-day cosmos were made with a precision that, for the first time, rivals that of inferences from the early universe by the European Space Agency’s orbiting Planck observatory. The new DES result (the tree, in the above metaphor) is close to “forecasts” made from the Planck measurements of the distant past (the seed), allowing scientists to understand more about the ways the universe has evolved over 14 billion years.

“This result is beyond exciting,” said Scott Dodelson of Fermilab, one of the lead scientists on this result. “For the first time, we’re able to see the current structure of the universe with the same clarity that we can see its infancy, and we can follow the threads from one to the other, confirming many predictions along the way.”

It took two years on a supercomputer to simulate 1.2 microseconds in the life of the HIV capsid, a protein cage that shuttles the HIV virus to the nucleus of a human cell. The 64-million-atom simulation offers new insights into how the virus senses its environment and completes its infective cycle.

The findings are reported in the journal Nature Communications.