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Target Selection and Validation of DESI Luminous Red Galaxies
- Source :
- AJ 165 58 (2023)
- Publication Year :
- 2022
-
Abstract
- The Dark Energy Spectroscopic Instrument (DESI) is carrying out a 5-year survey that aims to measure the redshifts of tens of millions of galaxies and quasars, including 8 million luminous red galaxies (LRGs) in the redshift range of $0.4<z<{\sim}\,1.0$. Here we present the selection of the DESI LRG sample and assess its spectroscopic performance using data from Survey Validation (SV) and the first 2 months of the Main Survey. The DESI LRG sample, selected using $g$, $r$, $z$, and $W1$ photometry from the DESI Legacy Imaging Surveys, is highly robust against imaging systematics. The sample has a target density of 605 deg$^{-2}$ and a comoving number density of $5\times10^{-4}\ h^3\mathrm{Mpc}^{-3}$ in $0.4<z<0.8$; this is a significantly higher density than previous LRG surveys (such as SDSS, BOSS and eBOSS) while also extending to $z \sim 1$. After applying a bright star veto mask developed for the sample, $98.9\%$ of the observed LRG targets yield confident redshifts (with a catastrophic failure rate of $0.2\%$ in the confident redshifts), and only $0.5\%$ of the LRG targets are stellar contamination. The LRG redshift efficiency varies with source brightness and effective exposure time, and we present a simple model that accurately characterizes this dependence. In the appendices, we describe the extended LRG samples observed during SV.<br />Comment: AJ, resubmission, 25 pages, 22 figures, 4 tables, one of a suite of 8 papers detailing targeting for DESI
Details
- Database :
- arXiv
- Journal :
- AJ 165 58 (2023)
- Publication Type :
- Report
- Accession number :
- edsarx.2208.08515
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.3847/1538-3881/aca5fb