Scientists have gained fresh insights into how the universe is expanding and the role of dark energy—a mysterious force making that expansion happen. This knowledge comes from an extensive analysis of data collected over six years by the Dark Energy Camera (DECam), which is attached to the Víctor M. Blanco telescope in Chile.
During its operation from 2013 to 2019, the Dark Energy Survey (DES) gathered observations of one-eighth of the night sky over 758 nights. It recorded data from 669 million galaxies, some billions of light-years away from Earth. This analysis is groundbreaking because it combines four different ways of studying dark energy, enhancing scientists’ understanding of this enigmatic force that makes up about 68% of the universe.
Regina Rameika, an official at the Department of Energy, noted that long-term research like this offers new insights into cosmic mysteries. The findings have doubled the understanding of how dark energy works, pushing the boundaries of current cosmological models.
The story of dark energy began in 1998 when astronomers noticed that distant supernovas were speeding away from us faster than expected. Edwin Hubble had confirmed earlier that the universe is expanding, but this was the first indication that the expansion is accelerating. Since that pivotal moment, scientists have realized that dark energy isn’t just a theoretical idea—it’s a significant part of our universe’s makeup.
In their recent analysis, the DES team looked at Type Ia supernovas and other methods, like weak gravitational lensing, galaxy clustering, and baryon acoustic oscillations. All this information allowed them to trace the distribution of matter over the last six billion years. They compared their findings with two main cosmological models: the Lambda Cold Dark Matter (LCDM) model and the evolving dark energy model (wCDM).
Interestingly, while most of their findings aligned with these models, one aspect didn’t: the way matter clusters in the current universe. There was a marked difference between what was observed and what the models predicted. This discrepancy has sparked discussions among scientists about the need for new theories or adjustments to existing ones.
The next phase for the DES will build on this work by integrating DECam data with observations from the upcoming Vera C. Rubin Observatory, which will gather data from around 20 billion galaxies over ten years. This collaboration promises to offer even deeper insights into the universe’s history and the nature of dark energy.
As Chris Davis, a director at the National Science Foundation, observed, these ongoing developments highlight how the DES has been transformative. The Vera C. Rubin Observatory is set to further enhance our grasp of gravity and dark energy.
The team’s findings have been shared in the journal Physical Review D and are available for further reading on arXiv.
