论文标题
目标选择和验证DESI发光红星系
Target Selection and Validation of DESI Luminous Red Galaxies
论文作者
论文摘要
黑暗能源光谱仪器（DESI）正在进行5年的调查，旨在测量数以百万计的星系和类星体的红移，包括800万发光红星系（LRGS），在$ 0.4 <z <z <z <Z <{\ sim}} \，1.0 $的红移范围内。在这里，我们介绍了DESI LRG样本的选择，并使用调查验证（SV）和主要调查的前两个月的数据评估其光谱性能。 Desi LRG样本使用$ g $，$ r $，$ z $和$ W1 $的光度法从DESI传统成像调查中进行，非常强大，可抵抗成像系统。该样品的目标密度为605 v $^{ - 2} $，并且合并的数字密度为$ 5 \ times10^{ - 4} \ h^3 \ Mathrm {mpc}^{ - 3} $ in $ 0.4 <z <z <0.8 $;这比以前的LRG调查（例如SDS，Boss和Eboss）的密度要高得多，同时也扩展到$ z \ sim 1 $。在为样品开发出明亮的星星否决面具后，观察到的LRG目标中的$ 98.9 \％$产生了自信的红移（灾难性的失败率为$ 0.2 \％$ $ $ 0.2 \％$ $），而LRG目标的0.5 \％$ $ $ $。 LRG红移效率随源亮度和有效的暴露时间而变化，我们提出了一个简单的模型，可以准确地表征这种依赖性。在附录中，我们描述了SV期间观察到的扩展LRG样品。
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.
