Baryon Oscillation Spectroscopic Survey (BOSS) is a spectroscopic survey of the night sky that aims to map the large-scale structure of the Universe. The survey is being conducted as part of the Sloan Digital Sky Survey III (SDSS-III). BOSS will observe galaxies and quasars over an area of 10,000 square degrees, more than twice the size of SDSS-I/II, in order to map the distribution of matter in both space and time.
The key scientific goal of BOSS is to measure the baryon acoustic oscillation (BAO) signal in order to constrain cosmological parameters such as the dark energy equation of state and neutrino mass. The BAO signal is a feature in the clustering pattern of matter that arises due to sound waves propagating through the early Universe. Measuring this signal provides a standard ruler with which we can probe the expansion history of the Universe and test models of cosmic acceleration.
In addition to measuring BAOs, BOSS will also obtain better measurements of other cosmological parameters such as the galaxy power spectrum amplitude, shape, and growth rate; improve our understanding of galaxy formation and evolution; detect backreaction effects on scales larger than previously probed; find new types of astronomical objects; and make many other discoveries.
BOSS observations began in September 2008 using dedicated 2.5 meter telescopes at Apache Point Observatory in New Mexico, USA. The survey will continue until 2014, after which it will be succeeded by eBOSS (extended BOSS), a similar spectroscopic survey that will further probe BAOs out to redshifts z~2.3 using newly commissioned robotic fiber positioners on APO’s 3.5 meter telescope.