Scientists have analysed 140 million galaxies across six billion years of cosmic history in the most comprehensive study yet of the mysterious force accelerating the expansion of the universe.
The Dark Energy Survey collaboration released results from its complete six-year dataset, producing constraints on how the universe behaves that are more than twice as strong as previous analyses.
Dark energy accounts for approximately 70 per cent of the universe’s total content, yet remains one of the most poorly understood phenomena in physics.
The findings largely support the standard model of cosmology, in which dark energy density remains constant over time. Researchers also tested an extended model allowing dark energy to vary, but found it fit the data no better than the standard model.
Professor Ofer Lahav from UCL, former co-chair of the DES Science Committee, said it was exciting to see results from the full dataset more than two decades after the project was conceived. He noted that future analyses would test the possibility of evolving dark energy.
The survey combined four different methods of measurement for the first time — baryon acoustic oscillations, type-Ia supernovae, galaxy clusters and weak gravitational lensing — as originally proposed when the project began 25 years ago.
UCL’s Astrophysics Group has been involved since 2004, with the optical corrector installed on the telescope in Chile assembled at the university’s laboratory.
The collaboration includes more than 400 scientists from 35 institutions across seven countries.
The analysis paves the way for upcoming large-scale surveys including LSST-Rubin and the European Space Agency’s Euclid mission.
