The Accelerating Universe: Early Results From the Dark Energy Survey

The fact that the expansion of the universe is accelerating is a discovery that earned the 2011 Nobel Prize in physics. Is it caused by a new "dark energy," or do we need to modify Einstein's General Relativity? If it is a new form of energy, is it constant or changing in time? Addressing these questions is the primary goal of the Dark Energy Survey (DES). After achieving first light in 2012, followed by months of commissioning and science verification, DES recently completed its third season of science observations at the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory in Chile. The DES Collaboration built a new 570-megapixel digital imager, the Dark Energy Camera (DECam), to carry out a deep, wide survey over the course of five (5) years---observing thousands of Type-Ia supernovae and hundreds of millions of galaxies. The thick, red-sensitive imager will allow us to see more supernovae and galaxies at higher redshift than previous surveys, like the Sloan Digital Sky Survey (SDSS). These observations will provide a suite of cosmological signatures: the Supernova Hubble diagram, galaxy cluster number counts, large-scale galaxy clustering and gravitational lensing. With this data, we will probe both the cosmic expansion history and the growth of large-scale structures, and thus explore the nature of dark energy. Nord will discuss the motivation for DES, the first years of operation and recent results, including maps of dark matter, dwarf galaxy discoveries and strong lens searches and confirmations.