Latest dark energy survey data suggest possible variations in dark energy over time

New research using the Dark Energy Survey (DES) final dataset suggests a potential inconsistency in the standard universe model known as λCDM. If confirmed, these discoveries could fundamentally alter our understanding of the universe.

The DES was carried out using the 570 megapixel division of the Energy Manufacturing Dark Energy Camera (Decam), mounted on the Víctor 4-meter telescope of the National Science Foundation at the Celerotoro Intersection Station in Chile, a program by NSF Noirab.

The λCDM (Lambda-CDM) model has been the basis of modern cosmology for some time, and it successfully explains the large-scale structure of the universe. It proposes that 95% of cosmos consists of dark matter (25%) and dark energy (70%). Only 5% of the universe is made up of ordinary matter.

Dark energy, represented by the cosmic constant (λ), is thought to promote accelerated expansion of the universe, and maintains a constant energy density over time. However, in a paper published on the ARXIV preprint server and a talk at the American Physical Society’s Global Physics Summit in Anaheim, California, new results from the Dark Energy Survey (DES) suggest a departure from this assumption, suggesting that dark energy may evolve over time. These findings are consistent with previous research and strengthen their importance.

DES is an international collaboration consisting of over 400 scientists from over 25 agencies, led by the US Department of Energy’s Fermi National Accelerator Research Institute. The DES was carried out using a 570-megapixel Energy Manufacturing Dark Energy Camera (DECAM) and is mounted on the National Science Foundation (NSF) Víctor M. Blanco 4-Meter telescope.

By obtaining data from 758 nights over six years, DES scientists mapped almost one-eighth area of ​​the sky. The project employs multiple observation techniques, including supernova measurement, galaxy clustering analysis, and weak gravity lenses, to study dark energy.

Two important DES measurements – baryon acoustic vibration (BAO) and distance measurements of explosive stars (type IA supernova) – track the universe’s enlarged history. Bao refers to a standard cosmic ruler formed by early universe sound waves, with peaks spanning approximately 500 million light years. Astronomers can measure these peaks over several periods of universe history to see how dark energy has expanded the scale over time.

Santiago Avila, Spanish Centre for Energy and Environmental Technology Research (CIEMAT), said he was in charge of the BAO analysis for DES.

Type IA supernova acts as a “standard candle.” This means that essentially bright is known. Therefore, their apparent brightness is combined with information about the host galaxy to allow scientists to perform accurate distance calculations. In 2024, DES published the most extensive and detailed supernova dataset to date, providing highly accurate measurements of space distance. These new findings from the combined supernova data and BAO data independently confirm the anomalies found in the 2024 supernova data.

By integrating DES measurements with cosmic microwave background data, researchers infer the properties of dark energy, and the results suggest that they evolve time. When verified, this implies a dynamic phenomenon in which the cosmological constant, dark energy, is not ultimately constant and requires a new theoretical framework.

“The results are interesting as they suggest physics beyond the standard models of cosmology,” says Juan Mena Fernandez of the Institute for Subatomic Physics and Cosmology in Grenoble, France. “If more data supports these findings, we may be on the brink of a scientific revolution.”

Although current results are still inconclusive, future analyses that incorporate additional DES probes, such as Galaxy Clustering and weak lenses, will need to enhance the evidence. Similar trends have emerged from other major cosmological projects, such as Dark Energy Spectroscopy (DESI).

“These results represent years of collaboration to extract cosmological insights from DES data,” says Jesse Muir of the University of Cincinnati. “There’s still a lot to learn and it’s exciting to see how understanding evolves as new measurements become available.”

The final DES analysis, expected later this year, will incorporate additional cosmological probes to cross-check the findings and improve the constraints of dark energy. The scientific community is eagerly eagerly awaiting these results as it can pave the way for a paradigm shift in cosmology.