The Dark Energy Survey

Josh Frieman

I will overview the Dark Energy Survey (DES) project, highlight its early science results (both cosmological and astrophysical), and discuss its on-going activities and plans. DES was designed to address the questions: why is the expansion speeding up? Is cosmic acceleration due to dark energy or does it require a modification of General Relativity? If dark energy, is it the energy density of the vacuum (Einstein's cosmological constant) or something else? DES is addressing these questions by measuring the history of cosmic expansion and the growth of structure through four complementary techniques: galaxy clusters, the large-scale galaxy distribution, gravitational lensing, and supernovae, as well as through cross-correlation with other data sets. The DES collaboration built the 570-megapixel Dark Energy Camera for the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory in Chile to carry out a deep grizY survey over 5000 sq. deg. and a time-domain survey that will discover several thousand supernovae. The survey started in Aug. 2013 and is now in its fourth survey season.