The Dark Energy Spectroscopic Instrument (DESI) has capped off the first seven months of its survey run by smashing through all previous records for three-dimensional galaxy surveys, creating the largest and most detailed map of the universe ever. Yet it’s only about 10% of the way through its five-year mission. Once completed, that phenomenally detailed 3D map will yield a better understanding of dark energy, and thereby give physicists and astronomers a better understanding of the past – and future – of the universe. Meanwhile, the impressive technical performance and literally cosmic achievements of the survey thus far are helping scientists reveal the secrets of the most powerful sources of light in the universe.
DESI is an international science collaboration managed by the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) with primary funding for construction and operations from DOE’s Office of Science.
DESI scientists are presenting the performance of the instrument, and some early astrophysics results, this week at a Berkeley Lab-hosted webinar called CosmoPalooza, which will also feature updates from other leading cosmology experiments.
“There is a lot of beauty to it,” said Berkeley Lab scientist Julien Guy, one of the speakers. “In the distribution of the galaxies in the 3D map, there are huge clusters, filaments, and voids. They’re the biggest structures in the universe. But within them, you find an imprint of the very early universe, and the history of its expansion since then.”
DESI has come a long way to reach this point. Originally proposed over a decade ago, construction on the instrument started in 2015. It was installed at the Nicholas U. Mayall 4-meter telescope at Kitt Peak National Observatory near Tucson, Arizona. Kitt Peak National Observatory is a program of the National Science Foundation’s (NSF) NOIRLab, which the Department of Energy contracts with to operate the Mayall Telescope for the DESI survey. The instrument saw first light in late 2019. Then, during its validation phase, the coronavirus pandemic hit, shutting down the telescope for several months, though some work continued remotely. In December 2020, DESI turned its eyes to the sky again, testing out its hardware and software, and by May 2021 it was ready to start its science survey.
But work on DESI itself didn’t end once the survey started. “It’s constant work that goes on to make this instrument perform,” said physicist Klaus Honscheid of Ohio State University, co-Instrument Scientist on the project, who will deliver the first paper of the CosmoPalooza DESI session.
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