International collaboration Sloan Digital Sky Survey (SDSS-III), today presented in six papers published simultaneously in the digital repository arXiv, obtained the most precise measurements to date of the distances to 300,000 galaxies reaching the distant universe. These results, offer an unprecedented look at the time the expansion of the universe began to accelerate, whose discovery was made the Nobel Prize in Physics last year.
After more than two years of project work Baryon Oscillation Spectroscopic Survey (BOSS), a project of the SDSS-III collaboration involving scientists, the results are now presented. Today we have obtained the most precise measurements to date of the distances to 300,000 galaxies reaching the distant universe. One of the most surprising discoveries of the last two decades in astronomy, awarded the Nobel Prize for Physics in 2011, was the realization that our universe is not only expanding but that expansion is accelerating, possibly as a result of action of the so-called dark energy, whose nature is unknown.
The purpose of the BOSS project to try to address this problem was to perform a wide mapping of the greater number of galaxies with accurate measurements of their distances. From these measurements, astronomers can deduce the history of the universe’s expansion and its rate of acceleration.
BOSS started taking data in mid-September 2009 with a new spectrograph attached to the 2.5-meter telescope of the SDSS in the Apache Point Observatory in New Mexico, USA. In just two and a half, this experiment has measured the exact positions of 300,000 galaxies across the sky, which can be traced back to the past of our universe, to more than 6,000 million years. BOSS will continue to collect data until 2014, when it will complete the ultimate mapping, which will triple the size of which has been analyzed so far.
The sky survey conducted by BOSS reproduces a map of galaxies and clusters of galaxies grouped in walls and filaments, with huge gaps that separate these structures. All these structures arose from small variations in density in the early Universe that bore the stamp of the baryon acoustic oscillations (BAO), a sound wave that spread through the early universe through matter, which later begin to collapse to form galaxies.
Billions of years later the track of the BAO can still be recognized in the Universe. This pattern can be interpreted as a cosmic fingerprint reflected in the distribution of galaxies. The details of this fingerprint can be measured parameters of the Universe and the properties of dark energy. In other words, in the same way that fingerprints are unique to each person, the cosmic fingerprint to determine how the universe. With the data taken to date, BOSS has been able to measure the BAO with an error of 2%, more accurate measurement of this data on to date. The map produced by BOSS can see the universe when I was half its current age and see when it begins to accelerate its expansion.