(July 9, 2015) Dark matter may find it tougher to hide in our universe.
An international team of researchers has developed a new map of the distribution of dark matter in the universe using data from the Dark Energy Survey (DES).
The DES, underway at the Blanco telescope in Chile, is a cosmological galaxy survey that will map approximately an eighth of the visible sky. The primary aim of the DES is to better characterize dark energy – the source of the observed accelerated expansion of the universe. But one of the ways of doing this is through studying the distribution and evolution of another scientific mystery: dark matter. Scientists estimate that ordinary atomic matter makes up only one-fifth of the total mass in the universe. The remaining mass is dark – “dark” because it does not absorb or emit light.
Scientists need a precise measurement of all the matter in the universe and where it is located to perform cosmological experiments accurately, said Vinu Vikraman, a postdoctoral researcher at the U.S. Department of Energy’s Argonne National Laboratory and co-author of the study.
“We don’t know what dark matter really is or how to directly locate it in the universe,” Vikraman said. “This map will act as a valuable tool for cosmology to answer some of these questions, including those related to dark energy.”
To indirectly detect dark matter, the scientists constructed a “mass map” using weak gravitational lensing shear measurements made by the DES. Gravitational lensing refers to the bending of light by the mass surrounding galaxies. This bending creates a distortion, or shear, of the galaxy’s shape, which scientists can then measure to determine the density and matter distribution of the lens.