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The Dark Energy Survey collected data on hundreds of millions of galaxies over six years to deepen our understanding of the expansion history of the universe. |Image source: CTIO/NOIRLab/DOE/NSF/AURA
A six-year survey covering 669 million galaxies reveals dark energythe mysterious phenomenon that drives the accelerated expansion of the universe.
This landmark survey paints a complex picture of our understanding of the universe, showing that both major cosmological theories are equally suited to new observations of the expansion of the universe. However, these two theories are still not enough to explain why matter in the universe accumulates in this way, suggesting that more work needs to be done.
The Dark Energy Survey (DES) analysis combines four types of data collected by the Victor M. Blanco Telescope in Chile, covering about one-eighth of the sky. The study focused on the past and present expansion of the universe, tightening the constraints on the expansion model by about twice as much as previous studies.
“These results from the Dark Energy Survey shed new light on our understanding of the universe and its expansion,” Regina RamecaThe deputy director of the U.S. Department of Energy’s Office of High Energy Physics said in a report statement. “They show how long-term investments in research and combining multiple types of analysis can provide insights into some of the biggest mysteries in the universe.”
expand our knowledge
Dark energy is thought to account for about 70% of the total energy in the universe, but astronomers still know very little about its true nature. Scientists developed this concept to explain the observation that the universe is expanding at an ever-accelerating rate. DES is one of several collaborative projects developed to study this phenomenon in more detail.
Scientists used the Victor M. Blanco Telescope in Chile to observe the universe’s expansion rate in four different ways. |Image source: CTIO/NOIRLab/NSF/AURA/T. Masopoulos
In a new paper posted to a preprint server arXiv On January 21, DES scientists used four markers to detect the expansion of the universe: baryon acoustic oscillations, fluctuations in the density of normal matter throughout the universe; Type Ia supernovae, stellar explosions that help scientists measure the distances of cosmic objects; galaxy clusters; weak gravitational lensing, which occurs when galaxy clusters distort space-time, distorting the apparent shape of objects behind them. A series of 18 supporting papers explore these findings in detail.
Overall, the data and analysis are consistent with previous dark energy studies, although the new work imposes tighter constraints on models of how the universe behaves. The data are mostly consistent with the Standard Model of cosmology, in which the density of dark energy is constant. The data also fit a related model in which dark energy density changes with time, but it did not fit better than the Standard Model.
“It’s an incredible feeling to see these results based on all the data and all four probes of the DES program,” said the study co-author. Zhang YuanyuanAstronomers at the National Science Foundation’s NOIRLab, which manages the telescope, said in a statement. “This is something I only dared to dream about when DES started collecting data, and now it’s a dream come true.”
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Although the fit between the data and the standard model is relatively good, some problems remain. The team adds that the pattern of galaxy clusters is still not entirely consistent with the predictions of the Standard Model, but it is not different enough to conclude that the Standard Model is wrong.
Still, DES researchers will continue to test this and other dark energy models Vera Rubin Observatory in Chile to further refine our understanding of this mysterious phenomenon.
“Rubin’s unprecedented survey of the southern sky will enable new gravity tests and reveal dark energy,” chris davisNSF NOIRLab program director said in a statement.
