The Dark Energy Survey

The Dark Energy Survey

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DES Science

Most experts believe that nothing short of a revolution in our understanding of fundamental physics will be required to achieve a full understanding of the cosmic acceleration. For these reasons, the nature of dark energy ranks among the most compelling of all outstanding questions in physical science. These circumstances demand an ambitious observational program to determine the dark energy properties as well as possible.

- Report of the Dark Energy Task Force

The dome of the Blanco telescope in Chile which will be home to the DES camera. The bright stars of the Milky Way, our own home galaxy, are arrayed across the sky in the background. The Large and Small Magellanic Clouds, satellite companion galaxies to the Milky Way, are visible on the left side of the image.
The Dark Energy Survey (DES) is using a powerful new imaging instrument, the Dark Energy Camera (DECam), to study the mystery of the acceleration of the expanding universe. In 2012, DECam was installed on the 4-meter Blanco telescope at the Cerro Tololo Inter-American Observatory high in the Chilean mountains. Over five years, the DES collaboration will use 525 nights of observation to carry out a high-precision, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey will image 5000 square degrees of the southern sky in 5 optical filters to obtain detailed information about each galaxy. A fraction of the time will be used to observe smaller patches of sky every few days to discover and study thousands of supernovae.

We are nearing completion of our second year of observing.

DES combines four probes of Dark Energy:

One of the strengths of DES is the ability to carry out all four probes of dark energy with a single facility. These probes are doubly complementary in the information they provide about the cause of cosmic acceleration. The first two (SN and BAO) constrain the expansion of the universe as a whole and are referred to as "purely geometric". The latter two (WL and GC) measure both the expansion of the universe and the growth of large-scale structures. Comparison of results from the first two and the last two probes could reveal that our understanding of gravity must be overhauled. In addition, inter-comparison of the results from all four methods will provide robust cross-checks and bolster confidence in the findings.