Max Planck Institute for Extraterrestrial Physics | 2016 July 14
[img3="This is one slice through the map of the large-scale structure of the Universe from the Sloan Digital Sky Survey and its Baryon Oscillation Spectroscopic Survey. Each dot in this picture indicates the position of a galaxy 6 billion years into the past.What are the properties of Dark Energy? This question is one of the most intriguing ones in astronomy and scientists are one step closer in answering this question with the largest three-dimensional map of the universe so far: This map contains 1.2 million galaxies in a volume spanning 650 cubic billion light years. Hundreds of scientists from the Sloan Digital Sky Survey III (SDSS-III) – including researchers at the Max Planck Institutes for Extraterrestrial Physics and for Astrophyics - used this map to make one of the most precise measurements yet of dark energy. They found excellent agreement with the standard cosmological model and confirmed that dark energy is highly consistent with a cosmological constant. ...
(Credit: Daniel Eisenstein and SDSS-III)"]http://www.mpe.mpg.de/6610883/zoom.jpg[/img3][hr][/hr]
These new measurements were carried out by the Baryon Oscillation Spectroscopic Survey (BOSS) programme of SDSS-III. Shaped by a continuous tug-of-war between dark matter and dark energy, the map revealed by BOSS allows astronomers to measure the expansion rate of the Universe by determining the size of the so-called baryonic acoustic oscillations (BAO) in the three-dimensional distribution of galaxies.
Pressure waves travelled through the young Universe up to when it was only 400,000 years old at which point they became frozen in the matter distribution of the Universe. The end result is that galaxies are preferentially separated by a characteristic distance, which astronomers call the BAO scale. The primordial size of the BAO scale is exquisitely determined from observations of the cosmic microwave background. ...
SDSS III Data Release 12
Dark Energy Measured with Record-Breaking Map of 1.2 Million Galaxies
Lawrence Berkeley National Laboratory | 2016 July 14
Astronomers Map 1.2 Million Galaxies to Study the Properties of Dark Energy
Sloan Digital Sky Survey | 2016 July 14
Most Precise 3D Map of Galaxies Supports Standard Cosmological Model
University of Barcelona, Spain | 2016 July 14
The Clustering of Galaxies in the Completed SDSS-III Baryon Oscillation Spectroscopic Survey - 14 Papers, arXiv