DESI at Kitt Peak Has Mapped More Galaxies Than All Previous 3D Surveys Combined
DOE Dark Energy Spectroscopic Instrument passes 7.5 million measured galaxy redshifts
13 January 2022
The Dark Energy Spectroscopic Instrument (DESI) has cataloged more galaxies than all other previous three-dimensional redshift surveys combined, measuring 7.5 million galaxies in only seven months since beginning science operations. The US Department of Energy's Lawrence Berkeley National Laboratory leads DESI, which is installed at Kitt Peak National Observatory, a program of NSF's NOIRLab, on the Nicholas U. Mayall 4-meter Telescope.
The Dark Energy Spectroscopic Instrument (DESI), has capped off the first seven months of its survey by smashing through all previous records for three-dimensional galaxy surveys, creating the largest and most detailed map of the Universe ever. The DESI survey has already cataloged over 7.5 million galaxies and is adding more at a rate of over a million a month. In November 2021 alone, DESI cataloged redshifts from 2.5 million galaxies. By the end of its run in 2026, DESI is expected to have over 35 million galaxies in its catalog, enabling an enormous, and so far unsurpassed, variety of cosmology and astrophysics research.
The primary task of the survey is to collect spectra of millions of galaxies across more than a third of the entire sky. By breaking down the light from each galaxy into its spectrum of colors, DESI can determine how much the light has been redshifted — stretched out toward the red end of the spectrum by the expansion of the Universe during the billions of years it traveled before reaching Earth. It is those redshifts that let DESI see the depth of the sky. The more redshifted a galaxy’s spectrum is, in general, the farther away it is. With a 3D map of the cosmos in hand, physicists can chart clusters and superclusters of galaxies. Those structures carry echoes of their initial formation, when they were just ripples in the infant cosmos. By teasing out those echoes, physicists can use DESI’s data to determine the expansion history of the Universe.
DESI is an international science collaboration managed by the US Department of Energy's (DOE) Lawrence Berkeley National Laboratory with primary funding for construction and operations from DOE’s Office of Science. DESI is installed at the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory (KPNO) near Tucson, Arizona. KPNO is a program of NSF's NOIRLab, and DOE contracts with NOIRLab to operate the Mayall Telescope for the DESI survey.
DESI is only about 10% of the way through its five-year mission. Once completed, the final 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.
“There is a lot of beauty to it,” says Berkeley Lab scientist Julien Guy of the map. “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 and it 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 started its science survey.
DESI is supported by the US Department of Energy’s Office of High Energy Physics; the US National Science Foundation, Division of Astronomical Sciences under contract to NSF’s NOIRLab; the Science and Technologies Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising-Simons Foundation; the French Alternative Energies and Atomic Energy Commission (CEA); the National Council of Science and Technology of Mexico; the Ministry of Economy of Spain; and DESI member institutions. The DESI scientists are honored to be permitted to conduct astronomical research on Iolkam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O'odham Nation.
NSF’s NOIRLab(National Optical-Infrared Astronomy Research Laboratory), the US center for ground-based optical-infrared astronomy, operates the International Gemini Observatory(a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and Vera C. Rubin Observatory(operated in cooperation with the Department of Energy’s SLACNational Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on Iolkam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O'odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.
Current DESI Member Institutions include: Aix-Marseille University; Argonne National Laboratory; Barcelona-Madrid Regional Participation Group; Brookhaven National Laboratory; Boston University; Brazil Regional Participation Group; Carnegie Mellon University; CEA-IRFU, Saclay; China Participation Group; Cornell University; Durham University; École Polytechnique Fédérale de Lausanne; Eidgenössische Technische Hochschule, Zürich; Fermi National Accelerator Laboratory; Granada-Madrid-Tenerife Regional Participation Group; Harvard University; Kansas State University; Korea Astronomy and Space Science Institute; Korea Institute for Advanced Study; Lawrence Berkeley National Laboratory; Laboratoire de Physique Nucléaire et de Hautes Énergies; Max Planck Institute; Mexico Regional Participation Group; New York University; NSF’s NOIRLab; Ohio University; Perimeter Institute; Shanghai Jiao Tong University; Siena College; SLAC National Accelerator Laboratory; Southern Methodist University; Swinburne University; The Ohio State University; Universidad de Los Andes; University of Arizona; University of Barcelona; University of California, Berkeley; University of California, Irvine; University of California, Santa Cruz; University College London; University of Florida; University of Michigan at Ann Arbor; University of Pennsylvania; University of Pittsburgh; University of Portsmouth; University of Queensland; University of Rochester; University of Toronto; University of Utah; University of Waterloo; University of Wyoming; University of Zurich; UK Regional Participation Group; Yale University.
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