After twenty years of data collection and five years of analysis by more than 100 astrophysicists, researchers from the Sloan Digital Sky Survey (SDSS) launched the largest three-dimensional map of the universe ever created. Detailed measurements of more than two million galaxies and quasars surveyed by the project cover a gap of 11 billion years of cosmic time.
“We are very familiar with the ancient history of the universe and its recent expansion, but there is a problematic gap in the 11 billion years,” explains University of Utah researcher Kyle Dawson, who led the SDSS team. “We are working to fill this gap and we are using this information to provide some of the most substantial advances in cosmology in the past decade,” he added.
Data collected from the cosmic microwave background radiation, in particular the measurement of the relative quantity of elements created just after the Big Bang, provided the scenario for the early years of the universe. The history of expansion over the past billions of years has been computed from galaxy maps and distance measurements, including earlier phases of the SDSS.
The new results came from the Baryon Spectroscopic Oscillation Study (extended Baryon Oscillation Spectroscopic Survey, or eBOSS). The analysis implemented redshift research, which measures the speeds at which galaxies move away from Earth due to the expansion of the universe, in order to infer their distances.
“Together, detailed analyzes of the eBOSS map and previous SDSS experiments provided the most accurate measurements of the history of expansion in the broadest range of all cosmic times,” says University of Waterloo researcher Will Percival, one of the eBOSS participants. . “These studies allow us to connect all these measures in a complete history of the expansion of the universe”.
The final map reveals the galactic filaments and the empty spaces that define the structure of the universe, from 300 thousand years after the Big Bang. From this map, the researchers measure patterns in the distribution of galaxies in key parameters with an accuracy greater than 1%. The study shows, for example, that the expansion of the universe began to accelerate about six billion years ago and has continued to grow faster ever since.
This accelerated expansion, according to the researchers, is due to the mysterious “dark energy”, consistent with Einstein’s General Theory of Relativity, but extremely difficult to reconcile with our current understanding of particle physics.
“By combining data from the SDSS with additional data from the cosmic microwave background, supernovae and other programs, we can simultaneously measure many fundamental properties of the Universe,” says researcher Eva-Maria Mueller, from the University of Oxford, who led the analysis of the results of the complete SDSS sample. The legacy map for future projects. Over the next decade, research may use its data to solve some of astrophysics’ dilemmas, or perhaps reveal new surprises.
Via: New York University / SDSS