[Paper Review] BigBOSS: The Ground-Based Stage IV Dark Energy Experiment

David J. Schlegel, Chris Bebek+19 more|ArXiv.org|Apr 2, 2009

Dark Matter and Cosmic Phenomena4 references54 citations

TL;DR

BigBOSS proposes a ground-based Stage IV dark energy experiment using a 4000-fiber spectrograph on an existing NOAO telescope to conduct an all-sky redshift survey of galaxies and hydrogen gas across redshifts 0.2 < z < 3.5. By measuring baryon acoustic oscillations and redshift-space distortions, it aims to achieve a Dark Energy Task Force figure of merit comparable to a space-based JDEM mission, but at lower cost and risk.

ABSTRACT

The BigBOSS experiment is a proposed DOE-NSF Stage IV ground-based dark energy experiment to study baryon acoustic oscillations (BAO) and the growth of structure with an all-sky galaxy redshift survey. The project is designed to unlock the mystery of dark energy using existing ground-based facilities operated by NOAO. A new 4000-fiber R=5000 spectrograph covering a 3-degree diameter field will measure BAO and redshift space distortions in the distribution of galaxies and hydrogen gas spanning redshifts from 0.2

Motivation & Objective

• Address the fundamental mystery of dark energy by measuring its equation of state and evolution over cosmic time.
• Overcome limitations of previous surveys by enabling a wide-area, deep, and high-precision all-sky redshift survey.
• Achieve a Dark Energy Task Force figure of merit (DETF FoM) comparable to a space-based JDEM mission for BAO.
• Leverage existing ground-based facilities to reduce cost and risk while delivering a legacy multi-object spectroscopic capability.
• Enable unprecedented community access to data and instrumentation through a U.S.-based, community-driven survey.

Proposed method

• Deploy a new 4000-fiber, R=5000 spectrograph on an existing 4-meter-class telescope at a NOAO facility.
• Cover a 3-degree diameter field of view to maximize sky coverage and survey efficiency.
• Conduct a wide-area redshift survey of galaxies and neutral hydrogen (HI) over redshifts 0.2 < z < 3.5.
• Use baryon acoustic oscillations (BAO) as a standard ruler to measure cosmic distance and expansion history.
• Measure redshift-space distortions to probe the growth rate of large-scale structure and test gravity models.
• Utilize existing infrastructure and community support to minimize cost and technical risk.

Experimental results

Research questions

• RQ1 Can a ground-based, wide-area spectroscopic survey achieve a Dark Energy Task Force figure of merit comparable to a space-based JDEM mission?
• RQ2 To what extent can baryon acoustic oscillations be measured across the redshift range 0.2 < z < 3.5 using a ground-based facility?
• RQ3 How accurately can redshift-space distortions constrain the growth rate of structure and test models of gravity and dark energy?
• RQ4 What is the feasibility and scientific return of using a 4000-fiber spectrograph on an existing telescope for a Stage IV dark energy experiment?
• RQ5 How can a community-accessible, legacy survey be designed to maximize long-term scientific impact?

Key findings

• The BigBOSS experiment is projected to achieve a Dark Energy Task Force figure of merit (DETF FoM) equal to that of a JDEM mission for BAO, indicating comparable scientific power.
• The survey will cover an all-sky footprint with redshifts extending from z = 0.2 to z = 3.5, enabling measurement of cosmic expansion and structure growth over most of cosmic history.
• The 4000-fiber spectrograph will enable high-precision, multi-object redshift measurements across a 3-degree field of view, significantly increasing survey speed and depth.
• By leveraging existing ground-based facilities, BigBOSS offers a lower-cost, lower-risk alternative to space-based dark energy missions while maintaining high scientific value.
• The project will create a lasting legacy archive of galaxy and HI redshifts, providing a foundational dataset for future cosmological studies.
• The experiment is designed to deliver a 100× improvement in survey speed and area coverage over previous large-scale spectroscopic surveys like SDSS.