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

A. Raichoor, J. Comparat, T. Delubac, J. -P. Kneib, Ch Yèche, K. S. Dawson, W. J. Percival, A. Dey, D. Lang, D. J. Schlegel, C. Gorgoni, J. Bautista, J. R. Brownstein, V. Mariappan, H. -J. Seo, J. L. Tinker, A. J. Ross, Y. Wang, G. -B. Zhao, J. MoustakasN. Palanque-Delabrouille, E. Jullo, J. A. Newmann, F. Prada, G. B. Zhu

Research output: Contribution to journalArticlepeer-review

127 Downloads (Pure)


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 gr versus rz colour–colour space and a cut on the g-band magnitude, to favour galaxies in the desired redshift range with strong [OII] emission. It provides a target density of 200 deg−2 on the North Galactic Cap and of 240 deg−2 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 σDV/DV = 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.
Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Early online date15 Jul 2017
Publication statusPublished - 11 Nov 2017


  • astro-ph.CO
  • astro-ph.GA
  • RCUK
  • STFC
  • ST/N000668/1
  • ST/N00180X/1


Dive into the research topics of 'The SDSS-IV extended Baryon Oscillation Spectroscopic Survey: final emission line galaxy target selection'. Together they form a unique fingerprint.

Cite this