Two teams of physicists at the U.S. Department of Energy’s Fermilab and Lawrence Berkeley National Laboratory (Berkeley Lab) have independently made the largest direct measurements of the invisible scaffolding of the universe, building maps of dark matter using new methods that, in turn, will remove key hurdles for understanding dark energy with ground-based telescopes.
The teams’ measurements look for tiny distortions in the images of distant galaxies, called “cosmic shear,” caused by the gravitational influence of massive, invisible dark matter structures in the foreground. Accurately mapping out these dark-matter structures and their evolution over time is likely to be the most sensitive of the few tools available to physicists in their ongoing effort to understand the mysterious space-stretching effects of dark energy. Both teams depended upon extensive databases of cosmic images collected by the Sloan Digital Sky Survey (SDSS), which were compiled in large part with the help of Berkeley Lab and Fermilab.
“These results are very encouraging for future large sky surveys. The images produced lead to a picture of the galaxies in the universe that is about six times deeper, or further back in time, than is available from single images,” says Huan Lin, a Fermilab physicist and member of the SDSS and the Dark Energy Survey (DES).