Sky Survey Casts Light on the Dark Universe

If you talked to any cosmologist today, you would most likely witness two conflicting emotions. The first is quite self-congratulatory as the community has collectively nailed down the precise quantities of each component in the Universe, using multiple independent observations. The second is one of panic, when they admit that the major dark constituents of the Universe that are inferred to exist remain elusive. The Dark Energy Survey (DES) is one of three optical imaging surveys in this decade’s hot competition to uncover the true nature of the dark side of our Universe. One way to demonstrate the future potential of these surveys is to identify and map dense clumps of dark matter through the distortions they cause in the perceived shapes of background galaxies. Chihway Chang of the Swiss Federal Institute of Technology (ETH) in Zurich, and Vinu Vikram of Argonne National Laboratory, Illinois, present a map of dark matter from the first 3% of data from DES, which is observing the Southern Sky over a full five-year mission [1, 2]. This very first glimpse reveals just how powerful this new sky survey will become in its quest to understand dark energy, which is driving the acceleration of the Universe and thereby affecting the distribution of the dark matter that they have mapped.