More than ten years ago, work began on the Dark Energy Survey (DES) project, the purpose of which was to create a map of the universe to search for evidence to help understand the nature of dark energy.
At a recent meeting of the American Astronomical Society in New Orleans, The final results of DES, prepared by over 100 scientists, were announced. Dark energy, which makes up about 70% of the observed universe, remains a mystery, but its influence is noticeable on a grandiose scale as it causes an accelerated expansion of the universe.
The announcement in New Orleans revealed data that could bring us closer to understanding this form of energy. These data allow for the examination of the hypothesis of the cosmological constant, which was proposed by Albert Einstein in 1917. Previously considered a mistake, the cosmological constant can now explain dark energy if its value is positive.
The results of DES are the culmination of decades of work by scientists from around the world and provide one of the best measurements of the so-called parameter “W” – the equation of the state of dark energy. Since the discovery of dark energy in 1998, determining the value of its equation of state has remained a fundamental issue.
The equation of state describes the ratio of pressure to the energy density of a substance, allowing for a better understanding of its nature. According to our best theory, the value of “W” should be exactly minus one (w = -1), which suggests that dark energy is an Einstein cosmological constant.
Using new techniques and observations of supernovae type IA, the DES team obtained data to make one of the most accurate measurements of “W”, which showed a value of -0.8. Although not exactly the predicted value of minus one, the uncertainty of these measurements is large enough to allow for a 5% probability of a value of minus one.
These results may signify the end of “large gap” models, in which the equation of state has a value more negative than one. In such models, the universe would