11 Billion Years of Our Universe's Expansion History
Sloan Digital Sky Survey | 2020 Jul 19
The Sloan Digital Sky Survey (SDSS) released today a comprehensive analysis of the largest three-dimensional map of the Universe ever created, filling in the most significant gaps in our possible exploration of its history.
“We know both the ancient history of the universe and its recent expansion history fairly well, but there’s a troublesome gap in the middle 11 billion years,” says cosmologist Kyle Dawson of the University of Utah, who leads the team announcing today’s results. “For five years, we have worked to fill in that gap, and we are using that information to provide some of the most substantial advances in cosmology in the last decade.”The SDSS map is shown as a rainbow of colours, located within the observable
Universe (the outer sphere, showing fluctuations in the Cosmic Microwave
Background). Image Credit: Anand Raichoor (EPFL), Ashley Ross
(Ohio State University) and the SDSS Collaboration
The new results come from the extended Baryon Oscillation Spectroscopic Survey (eBOSS), an international collaboration of more than 100 astrophysicists that is one of the SDSS’s component surveys. At the heart of the new results are detailed measurements of more than two million galaxies and quasars covering 11 billion years of cosmic time.
We know what the universe looked like in its infancy, thanks to the thousands of scientists from around the world who have measured the relative amounts of elements created soon after the Big Bang, and who have studied the cosmic microwave background. We also know its expansion history over the last few billion years from galaxy maps and distance measurements, including those from previous phases of the SDSS.
“Taken together, detailed analyses of the eBOSS map and the earlier SDSS experiments have now provided the most accurate expansion history measurements over the widest-ever range of cosmic time,” says Will Percival of the University of Waterloo, eBOSS’s Survey Scientist. “These studies allow us to connect all these measurements into a complete story of the expansion of the universe.” ...
Astrophysicists Fill in 11 Billion Years of Universe Expansion History
University of Portsmouth, UK | 2020 Jul 19
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Carnegie Institution for Science | 2020 Jul 20