[Paper Review] Dark Energy and Cosmic Sound: w(z) Surveys with the Gemini/Subaru Wide-Field Multi-Object Spectrograph

Karl Glazebrook, Daniel J. Eisenstein+3 more|arXiv (Cornell University)|Jul 19, 2005

Radio Astronomy Observations and Technology10 citations

TL;DR

This white paper proposes the Gemini/Subaru Wide-Field Multi-Object Spectrograph (WFMOS) to conduct a redshift survey of 2.6 million galaxies across 2000 square degrees with redshifts 0.5 < z < 3.3, enabling precise measurement of baryonic acoustic oscillations (BAO) in the large-scale structure. The survey aims to constrain the dark energy equation of state w(z) with precision an order of magnitude better than existing limits, using BAO features in the galaxy power spectrum to measure distance and expansion rate as a function of redshift.

ABSTRACT

This white paper gives an overview of the proposed Gemini/Subaru Wide-Field Multi-Object Spectrograph (WFMOS) and the proposed redshift surveys of 2.6 million galaxies with 0.5

Motivation & Objective

• To design a wide-field spectroscopic survey capable of measuring the dark energy equation of state w(z) with unprecedented precision.
• To probe baryonic acoustic oscillations (BAO) in the galaxy power spectrum across a broad redshift range (0.5 < z < 3.3).
• To deliver constraints on w(z) that are an order of magnitude more precise than current observational limits.
• To assess technical and scientific risks, calibration needs, and systematics in the BAO measurement pipeline for WFMOS.
• To position WFMOS within the broader context of baryon oscillation experiments and future dark energy surveys.

Proposed method

• Utilize the Wide-Field Multi-Object Spectrograph (WFMOS) on the Gemini and Subaru telescopes to obtain redshifts for 2.6 million galaxies over 2000 square degrees of sky.
• Measure the baryonic acoustic oscillation (BAO) scale in the clustering of galaxies to infer distance and expansion rate as a function of redshift.
• Use the angular diameter distance and Hubble parameter measurements derived from BAO to constrain the dark energy equation of state w(z).
• Apply statistical techniques to model and correct for systematics such as redshift-space distortions, galaxy bias, and observational selection effects.
• Leverage the wide area and depth of the survey to achieve high signal-to-noise detection of the BAO peak in the galaxy power spectrum.
• Integrate precursor observations and calibration strategies to ensure photometric and spectroscopic accuracy for cosmological inference.

Experimental results

Research questions

• RQ1 How precisely can the baryonic acoustic oscillation scale be measured in the galaxy power spectrum using a wide-area, deep spectroscopic survey?
• RQ2 What level of precision in w(z) can be achieved for the dark energy equation of state using BAO measurements from WFMOS?
• RQ3 What are the dominant systematics affecting BAO measurements in a large-scale galaxy redshift survey, and how can they be mitigated?
• RQ4 How do the WFMOS survey capabilities compare to other baryon oscillation experiments in terms of redshift coverage and cosmological sensitivity?
• RQ5 What are the technological and scientific risks associated with implementing the WFMOS survey for dark energy cosmology?

Key findings

• The proposed WFMOS survey can constrain the dark energy equation of state w(z) with precision an order of magnitude better than current observational limits.
• The survey will measure baryonic acoustic oscillations in the galaxy power spectrum over a redshift range 0.5 < z < 3.3 with high statistical significance.
• Distance-redshift and expansion-rate-redshift measurements derived from BAO will achieve high quantitative precision, enabling robust w(z) constraints.
• The survey’s wide area (2000 deg²) and depth (2.6 million galaxies) provide a unique combination for probing cosmic expansion history across a significant fraction of the observable universe.
• The method is robust to systematics when proper calibration and modeling are applied, with expected precision limited primarily by survey volume and signal-to-noise.
• WFMOS is positioned as a leading experiment in the baryon oscillation cosmology landscape, complementing and surpassing existing and planned surveys in key aspects of redshift coverage and depth.