This massive 3D map of 47 million galaxies could unlock dark energy

The project wrapped up ahead of schedule and delivered far more data than originally anticipated. This map is now the most detailed high-resolution 3D representation of the universe ever created. Researchers will use it to investigate dark energy, the mysterious force believed to make up about 70% of the cosmos.

47 Million Galaxies Mapped in Unprecedented Detail

Over five years of observations, DESI recorded more than 47 million galaxies and quasars along with 20 million stars. These measurements have already provided new insight into how the universe is structured and how it has changed over time, said Paul Martini, the instrument scientist during DESI construction and commissioning and a professor of astronomy at The Ohio State University.

"DESI has been a superb international collaboration, and its incredibly fruitful scientific results are a leading example of its impact on the broader scientific community," he said.

A Global Effort to Understand Dark Energy

DESI represents a large international collaboration involving more than 900 researchers (including 300 PhD students) from over 70 institutions. The project is led by the Department of Energy's Lawrence Berkeley National Laboratory. Scientists from Ohio State played a major role in key discoveries, from analyzing early results to uncovering unexpected changes in how dark energy behaves.

"Ohio State made the largest contributions to the instrumentation, operations and analysis infrastructure of any university group in DESI," said Klaus Honscheid, lead scientist of DESI instrument operations and a physics professor at Ohio State. "We are proud of our collaboration's world-leading results on dark energy, as well as pleased with the substantial, international media attention they have received."

Overcoming Challenges During the Survey

Completing the survey within five years was not without obstacles. One of the biggest setbacks came in 2022, when the Contras wildfire disrupted power and internet service at the observatory for months. Even so, the team managed to recover quickly and continue operations, said Ashley Ross, lead scientist for the DESI large-scale structure catalogs and an assistant research professor of physics at Ohio State.

"By coming up with creative solutions to address unforeseen problems, the high-quality data we collected each night was carefully and confidently used to obtain the exciting cosmological constraints that DESI is now known for," said Ross.

What the New Data Could Reveal About the Universe

With the full dataset now in hand, researchers have a much stronger foundation to test long-standing ideas about the balance between dark energy and matter. The results could lead to major changes in how scientists understand the universe and predict its future.

DESI has already gathered measurements from six times more galaxies and quasars than all previous surveys combined. The team will begin processing this complete dataset soon, with the first results from the full five-year survey expected in 2027.

Next Steps for DESI and Future Observations

Although the initial mission is complete, DESI will continue observing the sky through 2028. Future work will focus on harder-to-observe regions, helping build an even more detailed map of the cosmos. This expanded view could also improve studies of nearby structures such as dwarf galaxies and stellar streams, offering a clearer picture of how the universe formed and evolved, said Honscheid.

Meanwhile, researchers at Ohio State are continuing to refine measurements of dark energy using data from the first three years of observations. They are also working to improve how telescope time is used and to enhance the instrument's performance for future discoveries.

"A larger survey footprint will greatly improve our constraints on cosmological parameters and improve our dark matter program," said Honscheid. "But these achievements are only possible because the operations team worked incredibly hard to keep the survey progressing."

Contributors and Support

Other Ohio State contributors to DESI include Matthew Berno, Mikel Charles, Carl Coker, Rebecca Coles, Andrei Cuceu, Xinyi Chen, Mark Derwent, Ann Elliott, Jack Elvin-Poole, Lauren Ennesser, Kevin Fanning, Simon Filbert, Meagan Herbold, Jennifer Johnson, Naim Karacayli, Hui Kong, Claire Lamman, Thomas O'Brien, Daniel Pappalardo, Richard Pogge, Anna Porredon, Michael Rashkovetskyi, Jon Shover, Peter Taylor, Wynne Turner, David Weinberg, Molly Wolfson and Erik Zaborowski.

DESI is supported by the DOE Office of Science and by the National Energy Research Scientific Computing Center, a DOE Office of Science national user facility. Additional support for DESI is provided by the U.S. National Science Foundation; the Science and Technology 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 Secretariat of Science, Humanities, Technology and Innovation (SECIHTI) of Mexico; the Ministry of Science and Innovation of Spain; and by the DESI member institutions.

The DESI collaboration is honored to be permitted to conduct scientific research on I'oligam Du'ag (Kitt Peak), a mountain with particular significance to the Tohono O'odham Nation.