For the past six years, Fermi National Accelerator Laboratory has been part of an international effort to create an unprecedented survey of distant galaxies and better understand the nature of dark energy—the mysterious force accelerating the expansion of the universe.
After scanning about a quarter of the southern skies over 800 nights, the Dark Energy Survey finished taking data on Jan. 9. It ends as one of the most sensitive and comprehensive surveys of its kind, recording data from more than 300 million distant galaxies.
Fermilab, an affiliate of the University of Chicago, served as lead laboratory on the survey, which included more than 400 scientists and 26 institutions. The findings created the most accurate dark matter map of the universe ever made, shaping our understanding of the cosmos and its evolution. Other discoveries include the most distant supernova ever detected, a bevy of dwarf satellite galaxies orbiting our Milky Way, and helping to track the first-ever detection of gravitational waves from neutron stars back to its source.
According to Dark Energy Survey Director Rich Kron, a Fermilab scientist and professor at the University of Chicago, those results—and the scientists who made them possible—are where much of the real accomplishment of the Dark Energy Survey lies.
“The first generations of students and postdoctoral researchers on the Dark Energy Survey are now becoming faculty at research institutions and are involved in upcoming sky surveys,” Kron said. “The number of publications and people involved are a true testament to this experiment. Helping to launch so many careers has always been part of the plan, and it’s been very successful.”
Now the job of analyzing that data takes center stage, providing opportunities for new breakthroughs. The survey has already released a full range of papers based on its first year of data, and scientists are now diving into the rich seam of catalogued images from the first several years of data, looking for clues to the nature of dark energy.
The first step in that process, according to Fermilab scientist Josh Frieman, a professor at UChicago and former director of the Dark Energy Survey, is to find the signal in all the noise.
“We’re trying to tease out the signal of dark energy against a background of all sorts of non-cosmological stuff that gets imprinted on the data,” Frieman said. “It’s a massive ongoing effort from many different people around the world.”
More comprehensive results on dark energy are expected within the next few years.