Why is the universe expanding at an accelerated rate? The Dark Energy Survey hopes to answer that question by observing a section of space for the next five years. The project has been in development for more than 10 years and involves 25 institutions from six countries.
The Dark Energy Survey will spend the next five years looking at the southern sky, mapping out a 5,000-square degree region that covers nearly one-eighth of the sky, as it attempts to answer questions about dark energy. It is believed dark energy is the reason why the universe is expanding, but it cannot be observed, and researchers have to use indirect methods of observation to test the theory that dark energy is behind the acceleration of the expansion of the universe.
The astronomers will try to observe the effects of dark energy by counting the number of galaxy clusters, determining the distance of supernovae from Earth, examining the shapes of galaxies and fashioning a history of the expansion of the universe based on sound waves from when the universe was just 100,000 years old. These observational focal points will help researchers understand the distance between objects and the interaction between gravity and dark energy.
According to the researchers, gravity pulls galaxies together, creating clusters, whereas dark energy pulls them apart, and counting the number of these clusters can determine the effect of dark energy over time. Astronomers can measure a supernova’s brightness from when it first exploded until it fades away to determine the distance of the star from the Earth. The farther away a supernova is from when it first exploded, the faster the universe is expanding. Measuring the shape of galaxies will help researchers understand the interaction between dark energy and gravity in regards to dark matter, which makes up the majority of matter in the universe.
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The researchers note that early in the universe’s history, around when the universe was 400,000 years old, the interaction between light and matter created sound waves. These sound waves affected how galaxies were positioned and distributed throughout the universe, and the Dark Energy Survey will try to create a map of the history of expansion of the universe.
Members of the team will use the Dark Energy Camera, built by Fermilab, that will be mounted on the Victor M. Blanco telescope at the National Science Foundation’s Cerro Tololo Inter-American Observatory in Chile. The Dark Energy Camera is a digital camera that features five lenses and has a 570-megapixel sensor. The camera is capable of observing galaxies 8 billion light-years from Earth. The project will also include an interactive component where uses can view images taken by the Dark Energy Camera and learn more about different sections of the universe.
Ofer Lahav of University College London, head of the DES Science Committee, said in a statement, “We’re looking at this big galaxy map of the universe as a way of finding evidence for dark energy and characterizing its nature with cosmic epoch.” A video explaining more about the project, and its goals, can be viewed below.