The “cosmic ruler” by which astronomers measure distance in the Universe has been calibrated to one percent accuracy, which is the most precise calibration ever achieved. This study was done by a team at the Baryon Oscillation Spectroscopic Survey (BOSS) and has been submitted to the Monthly Notices of the Royal Astronomical Society. The results were presented this past week at the 223rd Meeting of the American Astronomical Society in Washington D. C.
The cosmic ruler is used as a standard measure to gauge how the size of the Universe has changed over time and other parameters by using galaxies that cluster at set intervals known as baryon acoustic oscillations (BAO) as the unit of measurement. Accuracy has increased dramatically over the last twenty years, back when fifty-percent was acceptable. BAOs and cosmic background radiation both play an integral role in determining the rate of expansion in the Universe and how it relates to dark energy. Ultimately, they found that dark energy stays relatively constant over time.
In addition to measuring the size of the Universe, they were also able to make some conclusions about the shape. Universe appears to be fairly flat overall, with only minor curvature. Fortunately, this means that simple geometry can be used to describe many of the Universe’s characteristics. The flat shape also supports the theory that the Universe is infinite and will be forever expanding.
The BOSS program has been surveying the sky since 2009 and has recorded over 1.2 million galaxies with red shifts between 0.2 and 0.7. No other program in the world has such a vast survey, and the survey still has about 6 more months to run. However, since they have the majority of data, over 90%, the team felt comfortable making their announcement. The data collected allows the team to look back at a point in time when expansion of the Universe was accelerating, about 6 billion years ago.
Future research will include the Dark Energy Spectroscopic Instrument (DESI), which will be much more sensitive than BOSS and help give an unprecedented survey of the sky. While BOSS will have cataloged 1.3 million galaxies when it completes its mission in June, DESI will be able to record 20 million galaxies and may be able to view the very beginning of cosmic radiation.