Extended Baryon Oscillation Spectroscopic Survey

Extended Baryon Oscillation Spectroscopic Survey
Name	Extended Baryon Oscillation Spectroscopic Survey
Abbreviation	eBOSS
Mission type	Astronomical survey
Operator	Sloan Digital Sky Survey Collaboration

Extended Baryon Oscillation Spectroscopic Survey is a cosmological spectroscopic program conducted as part of the Sloan Digital Sky Survey that measured redshifts of galaxies and quasars to map the large-scale structure of the Universe and to constrain models of dark energy and cosmology. The survey built on predecessor programs such as the Sloan Digital Sky Survey III and the Sloan Digital Sky Survey IV, and worked in concert with facilities like the Apache Point Observatory and analyses led by institutions including Lawrence Berkeley National Laboratory and University of California, Berkeley. eBOSS provided essential input for international projects such as the Dark Energy Survey and the Euclid mission, while engaging researchers from organizations like Yale University, Princeton University, Flatiron Institute, and Max Planck Society.

Overview

eBOSS extended the redshift reach of prior spectroscopic campaigns by targeting multiple tracer populations including luminous red galaxies associated with surveys like Two Micron All Sky Survey, emission-line galaxies studied with techniques developed at University of Arizona, and quasars that tie into research from European Southern Observatory programs. The survey strategy and science goals were coordinated through collaboration with projects at Harvard University, University of Washington, Carnegie Institution for Science, and FNAL partners, and its public data releases informed cosmological analyses performed by teams at Stanford University, University of Cambridge, and Kavli Institute for Cosmology. eBOSS observations exploited the Baryon acoustic oscillation signal first detected in analyses linked to Wilkinson Microwave Anisotropy Probe and later compared against constraints from Planck.

Instrumentation and Survey Design

The instrumentation leveraged the Sloan Foundation Telescope at Apache Point Observatory fitted with the BOSS spectrograph hardware upgraded under projects involving Brookhaven National Laboratory and Lawrence Berkeley National Laboratory. The fiber-fed spectrographs and plate systems were similar to those used in efforts by SDSS-III teams and were manufactured with contributions from Johns Hopkins University and University of Colorado Boulder engineers. Survey design principles drew on methodologies established by analysts from Columbia University, University of Michigan, and Carnegie Mellon University to optimize tile placements and fiber assignments, referencing statistical techniques from groups at Massachusetts Institute of Technology and California Institute of Technology.

Target Selection and Observations

Target selection combined photometric catalogs derived from imaging surveys such as Pan-STARRS and Wide-field Infrared Survey Explorer to identify tracers including luminous red galaxies linked to programs at University of Oxford and quasars vetted in coordination with National Optical Astronomy Observatory efforts. Selection algorithms incorporated cuts influenced by stellar population models from Max Planck Institute for Astronomy and redshift estimation approaches developed at University of Toronto and University of Chicago. Observing campaigns were executed by staff affiliated with New Mexico State University, University of Utah, and Stony Brook University, and scheduling strategies referenced time allocation policies like those used by Gemini Observatory and Kitt Peak National Observatory.

Data Processing and Catalogs

Data reduction pipelines were evolved from tools created by the SDSS software teams and adapted with contributions from Flatiron Institute and Carnegie Mellon University to produce calibrated spectra and redshift catalogs comparable to releases from SDSS Data Release 14 and successors. Catalog compilation incorporated cross-matching with external resources maintained by NASA, European Space Agency, and databases curated by Space Telescope Science Institute, enabling joint analyses with imaging data from Dark Energy Camera and spectroscopic follow-up from Keck Observatory. Quality assessment, systematic correction, and value-added catalogs were prepared by consortia including researchers at University of Pennsylvania, Rutgers University, and University of Illinois Urbana-Champaign.

Scientific Goals and Key Results

Primary goals included measurement of the baryon acoustic oscillation scale in multiple redshift bins to constrain the Hubble constant and the expansion history in the context of models like ΛCDM and alternatives investigated at Perimeter Institute. eBOSS produced BAO detections and growth-rate measurements that were compared with cosmic microwave background results from Planck and distance-ladder measurements associated with Hubble Space Telescope, influencing debates involving teams at Carnegie Observatories and University of Chicago. The quasar and Lyman-α forest analyses connected to research by Institute for Advanced Study and University of California, Santa Cruz provided new constraints on structure formation, while cross-correlation studies with weak lensing from Canada–France–Hawaii Telescope and cluster catalogs from South Pole Telescope refined tests of gravity investigated at Imperial College London.

Collaborations and Legacy

The collaboration assembled scientists from universities and laboratories including Princeton University, Yale University, University of California, Berkeley, Lawrence Livermore National Laboratory, and Max Planck Society, and maintained partnerships with surveys like DESI and missions like Euclid and Nancy Grace Roman Space Telescope. eBOSS data contributed to training pipelines and mock catalogs used by research groups at University of Tokyo and University of Bonn, and its methodologies influenced instrument planning at facilities such as LAMOST and Subaru Telescope. The public data releases supported educational initiatives at institutions like California Institute of Technology and outreach by museums including American Museum of Natural History.

Challenges and Future Extensions

Challenges included systematic errors from spectroscopic calibration that required mitigation strategies developed in coordination with teams at University of Cambridge and Max Planck Institute for Astrophysics, fiber-collision limitations addressed via tiling algorithms from Massachusetts Institute of Technology, and cosmic variance considerations discussed at conferences organized by American Astronomical Society. Future extensions and successor projects were planned in dialogue with consortia behind Dark Energy Spectroscopic Instrument, Euclid, and Vera C. Rubin Observatory, with proposals engaging researchers at Princeton University, Harvard University, and University of California, Santa Cruz to push redshift depth, tracer diversity, and cross-correlation science.

Category:Astronomical surveys