The SDSS-IV extended Baryon Oscillation Spectroscopic Survey: final emission line galaxy target selection

DOI: 
10.1093/mnras/stx1790
Publication date: 
01/11/2017
Main author: 
Raichoor, A.
IAA authors: 
Prada, F.
Authors: 
Raichoor, A.;Comparat, J.;Delubac, T.;Kneib, J. -P.;Yèche, Ch;Dawson, K. S.;Percival, W. J.;Dey, A.;Lang, D.;Schlegel, D. J.;Gorgoni, C.;Bautista, J.;Brownstein, J. R.;Mariappan, V.;Seo, H. -J.;Tinker, J. L.;Ross, A. J.;Wang, Y.;Zhao, G. -B.;Moustakas, J.;Palanque-Delabrouille, N.;Jullo, E.;Newmann, J. A.;Prada, F.;Zhu, G. B.
Journal: 
Monthly Notices of the Royal Astronomical Society
Refereed: 
Yes
Publication type: 
Article
Volume: 
471
Pages: 
3955-3973
Abstract: 

We describe the algorithm used to select the emission line galaxy (ELG) sample at z ̃ 0.85 for the extended Baryon Oscillation Spectroscopic Survey of the Sloan Digital Sky Survey IV, using photometric data from the DECam Legacy Survey. Our selection is based on a selection box in the g - r versus r - z colour-colour space and a cut on the g-band magnitude, to favour galaxies in the desired redshift range with strong [O II] emission. It provides a target density of 200 deg<SUP>-2</SUP> on the North Galactic Cap and of 240 deg<SUP>-2</SUP> on the South Galactic Cap (SGC), where we use a larger selection box because of deeper imaging. We demonstrate that this selection passes the extended Baryon Oscillation Spectroscopic Survey requirements in terms of homogeneity. About 50 000 ELGs have been observed since the observations have started in 2016, September. These roughly match the expected redshift distribution, though the measured efficiency is slightly lower than expected. The efficiency can be increased by enlarging the redshift range and with incoming pipeline improvement. The cosmological forecast based on these first data predict σ _{D_V}/D_V = 0.023, in agreement with previous forecasts. Lastly, we present the stellar population properties of the ELG SGC sample. Once observations are completed, this sample will be suited to provide a cosmological analysis at z ̃ 0.85, and will pave the way for the next decade of massive spectroscopic cosmological surveys, which heavily rely on ELGs. The target catalogue over the SGC will be released along with DR14.

Database: 
ADS
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032275628&doi=10.1093%2fmnras%2fstx1790&partnerID=40&md5=36f7f22dba24a952f7ccb7a8e59f2b5d
ADS Bibcode: 
2017MNRAS.471.3955R
Keywords: 
methods: data analysis;galaxies: distances and redshifts;galaxies: photometry;galaxies: stellar content;large-scale structure of Universe;cosmology: observations;Astrophysics - Cosmology and Nongalactic Astrophysics;Astrophysics - Astrophysics of Galaxies