Fermilab VMS
Scientists from the Dark Energy Survey (DES) collaboration have unveiled their most detailed study yet on the Universe’s expansion over the past six billion years. This international research effort, supported by the UK’s Science and Technology Facilities Council (STFC) and six UK universities, is led by the U.S. Department of Energy’s Fermi National Accelerator Laboratory.
The study combines multiple, independent measurements of the cosmos, effectively doubling the precision of previous DES studies. Importantly, the findings remain consistent with the standard model of cosmology, the most widely accepted theory explaining the Universe’s behavior.
Breakthrough in Cosmological Techniques
The findings amalgamate results from 18 separate studies, marking the first time four major techniques for studying dark energy have been brought together within a single experiment. This milestone was envisioned when DES was conceived 25 years ago.
Professor David Bacon, Director of the University of Portsmouth’s Institute of Cosmology and Gravitation, commented on the achievement:
“The beauty of the Dark Energy Survey has been bringing together several different types of observations of the cosmos, to learn about how the Universe expands. These results don’t happen automatically – they’re due to the hard work, joy and tears of hundreds of scientists, pressing forward together for 20 years.”
Among the techniques employed are weak lensing and galaxy clustering, two of the most powerful observational methods in cosmology. Weak lensing involves the subtle distortion of light from distant galaxies as it passes through gravitational fields, while galaxy clustering examines the spatial distribution of galaxies and their correlations.
Far-Reaching Science and International Collaboration
The DES collaboration conducted a comprehensive survey of the sky from 2013 to 2019, utilizing a specially constructed 570-megapixel Dark Energy Camera at the US National Science Foundation’s Cerro Tololo Inter-American Observatory in Chile. Over six years, scientists gathered images and data from hundreds of millions of distant galaxies, mapping about one-eighth of the sky.
Professor Michele Dougherty, Executive Chair of STFC, emphasized the significance of this work:
“This research shows the power of long-term international collaboration and UK investment in world-leading science. Dark energy remains one of the great unanswered questions in science. Studies like this demonstrate how bringing together different approaches can give us a clearer picture of our Universe and where future discoveries may lie.”
The Mystery of Dark Energy
The study’s measurements reveal how dark energy and dark matter have influenced the Universe’s evolution. However, a mystery persists. Although the data largely aligns with the standard model, a discrepancy in how matter clusters in the Universe remains. This discrepancy has become more pronounced with the inclusion of the full dataset.
Astrophysicists believe dark energy constitutes about 70% of the Universe’s mass-energy content, yet its nature remains elusive. The DES findings will be pivotal in exploring and testing alternative theories about gravity and dark energy.
A Century of Cosmic Discovery
Approximately 100 years ago, scientists discovered that distant galaxies appeared to be moving away from Earth, providing the first evidence of the Universe’s expansion. While it was initially expected that this expansion would slow due to gravity, observations in 1998 revealed that the expansion is actually accelerating, leading to the hypothesis of dark energy.
The DES collaboration, comprising over 400 astrophysicists, astronomers, and cosmologists from more than 35 institutions across seven countries, continues to push the boundaries of our understanding. UK contributions to the study include researchers from the University of Cambridge, University College London, University of Edinburgh, University of Nottingham, and University of Sussex.
Looking Ahead: New Frontiers in Astronomy
The UK, through the STFC, is also supporting research programs that will build on the DES collaboration’s work in future astronomical surveys, such as the Vera C. Rubin Observatory currently under construction in Chile. These efforts aim to deepen our understanding of dark energy and the Universe’s expansion.
As the DES collaboration prepares to integrate its latest findings with results from other dark energy experiments, the scientific community eagerly anticipates new insights into the fundamental forces shaping our cosmos.
