NOIRLab Nuggets
Testing Gravity with the Dark Energy Spectroscopic Instrument (DESI)
2 January 2025
The Dark Energy Spectroscopic Instrument (DESI) is an advanced spectrograph capable of measuring the redshifts of 5000 galaxies simultaneously. DESI is probing dark energy — the mysterious force that is causing the expansion of the Universe to accelerate.
With such a vast amount of data, other types of analysis can be done as well. Using the first year of DESI data (containing nearly six million galaxies spanning over 11 billion years of the history of the Universe), researchers created the largest 3D map of the Universe ever. Analyzing this map allowed researchers to test Einstein’s general theory of relativity over vast cosmic distances more precisely than has ever been possible. They found that the observed structure of the Universe matches very well with Einstein’s predictions of how gravity behaves at large scales, and their results place limits on other theories of gravity that have been proposed to explain dark energy. The study also places limits on the mass of a subatomic particle called a neutrino. Neutrinos are small, light, neutrally charged particles and the only fundamental particles whose mass has not been measured precisely.
“This research is part of one of the key projects of the DESI experiment — to learn about the fundamental aspects of our Universe at large scales, such as matter distribution and the behavior of dark energy, as well as fundamental aspects of particles,” says Stephanie Juneau, NSF NOIRLab astronomer and a member of the DESI collaboration. “By comparing the evolution of the matter distribution in the Universe with existing predictions, including Einstein’s general theory of relativity and competing theories, we're really tightening the possibilities on our models of gravity.”
The team will continue analyzing more data as they become available, refining their results and giving us even more information about the history of the Universe.
For more information, see the press release, “DESI Provides Best Test Yet of How Gravity Behaves at Cosmic Scales”.
Contacts
Rob Sparks
Senior Communications, Education and Engagement Specialist
NSF NOIRLab
Email: robert.sparks@noirlab.edu