Investigating Emission Line Galaxy Surveys with the Sloan Digital Sky Survey Telescope

TL;DR

This study evaluates galaxy selection methods for emission-line galaxy surveys with SDSS to enable BAO measurements at higher redshifts, confirming the feasibility of future large-scale ELG surveys for cosmological studies.

Contribution

It introduces and assesses new colour selection schemes for ELG identification in the SDSS and CFHT-LS photometry, demonstrating their effectiveness for future BAO surveys.

Findings

Achieved 75% redshift measurement efficiency with a new selection scheme.

Confirmed the feasibility of using SDSS BOSS spectrograph for high-redshift BAO detection.

Supported the potential of eBOSS for cosmological measurements at z~1.

Abstract

The Baryon Acoustic Oscillation (BAO) feature in the power spectrum of galaxies provides a standard ruler to probe the accelerated expansion of the Universe. The current surveys covering a comoving volume sufficient to unveil the BAO scale are limited to redshift $z \lesssim 0.7$. In this paper, we study several galaxy selection schemes aiming at building an emission-line-galaxy (ELG) sample in the redshift range $0.6<z<1.7$, that would be suitable for future BAO studies using the Baryonic Oscillation Spectroscopic Survey (BOSS) spectrograph on the Sloan Digital Sky Survey (SDSS) telescope. We explore two different colour selections using both the SDSS and the Canada France Hawai Telescope Legacy Survey (CFHT-LS) photometry in the u, g, r, and i bands and evaluate their performance selecting luminous ELG. From about 2,000 ELG, we identified a selection scheme that has a 75 percent redshift measurement efficiency. This result confirms the feasibility of massive ELG surveys using the BOSS spectrograph on the SDSS telescope for a BAO detection at redshift $z\sim1$, in particular the proposed eBOSS experiment, which plans to use the SDSS telescope to combine the use of the BAO ruler with redshift space distortions using emission line galaxies and quasars in the redshift $0.6<z<2.2$.