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Dark Energy Measured with Record-Breaking Map of 1.2 Million Galaxies

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deby Angela Guess

A recent release out of the Lawrence Berkeley National Laboratory reports, “A team of hundreds of physicists and astronomers have announced results from the largest-ever, three-dimensional map of distant galaxies. The team constructed this map to make one of the most precise measurements yet of the dark energy currently driving the accelerated expansion of the Universe. ‘We have spent five years collecting measurements of 1.2 million galaxies over one quarter of the sky to map out the structure of the Universe over a volume of 650 cubic billion light years,’ says Jeremy Tinker of New York University, a co-leader of the scientific team carrying out this effort. ‘This map has allowed us to make the best measurements yet of the effects of dark energy in the expansion of the Universe. We are making our results and map available to the world’.”

The release continues, “These new measurements were carried out by the Baryon Oscillation Spectroscopic Survey (BOSS) program of the Sloan Digital Sky Survey-III. Shaped by a continuous tug-of-war between dark matter and dark energy, the map revealed by BOSS allows scientists to measure the expansion rate of the Universe and thus determine the amount of matter and dark energy that make up the present-day Universe. A collection of papers describing these results was submitted this week to the Monthly Notices of the Royal Astronomical Society.”

It goes on, “BOSS measures the expansion rate of the Universe by determining the size of the baryonic acoustic oscillations (BAO) in the three-dimensional distribution of galaxies. The original BAO size is determined by pressure waves that travelled through the young Universe up to when it was only 400,000 years old (the Universe is presently 13.8 billion years old), at which point they became frozen in the matter distribution of the Universe. The end result is that galaxies have a slight preference to be separated by a characteristic distance that astronomers call the acoustic scale.”

Read more here.

Photo credit: Daniel Eisenstein and SDSS-III

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