eBOSS

eboss survey

Planned eBOSS coverage of the universe

 

 

 

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

Key Science Questions

  • How does the transition from deceleration to acceleration occur? Is it consistent with existing theories of dark energy?
  • How does structure grow during this epoch? Are there signs of violations of the general relativistic theory of gravity, which could be related to the acceleration?
  • Can we detect anomalies in the very largest scale clustering that could tell us about the earliest moments in the Universe’s history?
  • Can we detect the effects of cosmic neutrinos, and thus pin down the neutrino mass scale?
    What is the evolution of bright quasars of all luminosities out to redshift z = 3?

eBOSS Technical Details

  • 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

People

  • Principal Investigator: Jean-Paul Kneib (EPFL)
  • Survey Scientist: Will Percival (University of Portsmouth)
  • Instrument Scientist: Kyle Dawson (University of Utah)
  • Targeting Coordinator: Jeremy Tinker (New York University)
  • Tiling Coordinator: Hee-Jong Seo (Ohio State University)
  • Pipeline Coordinator: Stephen Bailey (LBNL)

eBOSS Sub-programs

eBOSS also includes two subprograms to follow up on other types of objects: the Time-Domain Spectroscopic Survey (TDSS) for variable objects, and the SPectroscopic IDentification of ERosita Sources (SPIDERS) for x-ray sources.

TDSS

Principal Investigators: Paul Green (SAO) and Scott Anderson (UW)

The Time-Domain Spectroscopic Survey (TDSS) will select time-variable targets for spectroscopic follow-up. These targets will include quasars and several classes of variable stars, some of which may reveal previously unidentified phenomena. By spectroscopically identifying the physical nature of 100,000 detected variables, TDSS will greatly enhance the power of these existing data sets to illuminate the physics of stars and quasars. Future photometric surveys (such as the Large Synoptic Survey Telescope) will leverage TDSS observations to classify their detections more robustly.

TDSS will additionally devote a number of fiber to “few-epoch spectroscopy” to study spectroscopic variability of special classes, such as double-peaked emission line quasars, broad-absorption line quasars, and dwarf carbon stars.

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

SPIDERS

Principal Investigators: Andrea Merloni and Kirpal Nandra (MPE)

The SPectroscopic IDentification of ERosita Sources (SPIDERS) survey will take spectra of 50,000 X-ray emitting quasars and X-ray cluster galaxies detected by eROSITA, a ground-breaking new X-ray telescope to be launched in 2014. Quasars emit copiously in X-rays, but some are obscured in visible light. This telescope combined with eBOSS follow-up will uncover this hidden population of obscured quasars. Because X-ray observations also allow robust measurements of black hole growth rates, eBOSS will provide the most complete measurements to date of the growth history of supermassive black holes. Meanwhile, SPIDERS observations of X-ray cluster galaxies will allow us to map the 3D distribution of these X-ray clusters — the most massive bound systems in the Universe, exceeding 1015 times the mass of our Sun, and key tracers of the growth of structure.

The combination of SPIDERS with the eBOSS large-scale structure 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.