Site Map


eBOSS Principal Investigator: Jean-Paul Kneib (EPFL)

Redshift diagram demonstrating gap eBOSS will fill.

The Extended Baryon Oscillation Spectroscopic Survey (eBOSS) will precisely measure the expansion history of the Universe throughout eighty percent of cosmic history, back to when the Universe was less than three billion years old, and improve constraints on the nature of dark energy. "Dark energy" refers the observed phenomenon that the expansion of the Universe is currently accelerating, which is most mysterious experimental result in modern physics.

eBOSS concentrates its efforts on the observation of galaxies and in particular quasars, in a range of distances (redshifts) currently left completely unexplored by other three-dimensional maps of large-scale structure in the Universe. In filling this gap, eBOSS will create the largest volume survey of the Universe to date. The figure to the right shows the region that will be newly mapped by the eBOSS project. This region corresponds to the epoch when the Universe was transitioning from deceleration due to the effects of gravity, to the current epoch of acceleration.

The combination of eBOSS with the SPIDERS X-ray selected sample of quasars, and the TDSS variability selected AGN sample, will create a unique window into the full population of quasars at all epochs to redshift z = 3.

Key Science Questions

eBOSS Technical Details

eBOSS at a glance
Dark-time observations
Fall 2014 - Spring 2020
1000 fibers per 7 deg2 plate
Wavelength: 360-1000 nm, resolution R~2000
375,000 luminous red galaxies over 7500 deg2, 0.6 < z < 0.8
375,000 luminous red galaxies over 7500 deg2, 0.6 < z < 0.8
260,000 emission line galaxies over 1500 deg2, 0.6 < z < 1.0
740,000 quasars over 7500 deg2, 0.9 < z < 3.5
1--2% distance measurements from baryon acoustic oscillations between 0.6 < z < 2.5