New DESI Results Weigh In On Gravity

The study also provided new upper limits on the mass of neutrinos, the only fundamental particles whose masses have not yet been precisely measured. Previous neutrino experiments found that the sum of the masses of the three types of neutrinos should be at least 0.059 eV/c². (For comparison, an electron has a mass of about 511,000 eV/c².) DESI's results indicate that the sum should be less than 0.071 eV/c², leaving a narrow window for neutrino masses.

The DESI collaboration shared their results in several papers posted to the online repository arXiv today. The complex analysis used nearly 6 million galaxies and quasars and lets researchers see up to 11 billion years into the past. With just one year of data, DESI has made the most precise overall measurement of the growth of structure, surpassing previous efforts that took decades to make.

Today's results provide an extended analysis of DESI's first year of data, which in April made the largest 3D map of our universe to date and revealed hints that dark energy might be evolving over time. The April results looked at a particular feature of how galaxies cluster known as baryon acoustic oscillations (BAO). The new analysis, called a "full-shape analysis," broadens the scope to extract more information from the data, measuring how galaxies and matter are distributed on different scales throughout space. The study required months of additional work and cross-checks. Like the previous study, it used a technique to hide the result from the scientists until the end, mitigating any unconscious bias.

"Both our BAO results and the full-shape analysis are spectacular," said Dragan Huterer, professor at the University of Michigan and co-lead of DESI's group interpreting the cosmological data. "This is the first time that DESI has looked at the growth of cosmic structure. We're showing a tremendous new ability to probe modified gravity and improve constraints on models of dark energy. And it's only the tip of the iceberg."