Astronomers working in the Sloan Digital Sky Survey (SDSS) have determined the expansion rate of the Universe through the data gathered from 140,000 distant quasars.
The researchers described the measurement gathered from these quasars as the most accurate measurement of the Universe's expansion rate for the last 13 billion years.
The SDSS used the Baryon Oscillation Spectroscopic Survey (BOSS) to measure the structure of the early universe by mapping the distribution of quasars in comparison with the available intergalactic hydrogen. The latest results on this study have combined the two methods using both quasars and intergalactic gas in order to successfully calculate the expansion rate of the universe.
The first analysis was conducted by Andreu Font-Ribera from the Lawrence Berkeley National Laboratory and he compared the number of quasars to the amount of hydrogen gas. A second analysis was performed by Timothée Delubac from the EPFL Switzerland and France's Centre de Saclay, and he identified the patterns made by the hydrogen gas to come up with the calculations of the mass's distribution in the early Universe. Combining the two analyses together, BOSS found out that the Universe was expanding at one percent per 44 million years, 10.8 billion years ago.
"If we look back to the Universe when galaxies were three times closer together than they are today, we'd see that a pair of galaxies separated by a million light-years would be drifting apart at a speed of 68 kilometers per second as the Universe expands," Font-Ribera said in a press release.
BOSS is capable of computing the expansion rate of the Universe at any given time because it could measure the size of baryon acoustic oscillations (BAO). BAO is an energy signature showing how matter is distributed and may produce sound waves present in the ancient Universe. This imprint is also present in other bodies, in the Universe including quasars, galaxies, and black holes.
This study was presented at the April 2014 meeting of the American Physical Society in Savannah, GA.
