Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Quasar Sample

By Gordon Richards, Xiaohui Fan, Heidi Jo Newberg, M. Strauss, D. V. vanden Berk, D. Schneider, Brian Yanny, Adam Boucher, S. Burles, Joshua A. Frieman and 11 more. 2002

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We describe the algorithm for selecting quasar candidates for optical spectroscopy in the Sloan Digital Sky Survey. Quasar candidates are selected via their nonstellar colors in ugriz broadband photometry and by matching unresolved sources to the FIRST radio catalogs. The automated algorithm is sensitive to quasars at all redshifts lower than z ∼ 5.8. Extended sources are also targeted as low-redshift quasar candidates in order to investigate the evolution of active galactic nuclei (AGNs) at the faint end of the luminosity function. Nearly 95% of previously known quasars are recovered (based on 1540 quasars in 446 deg2). The overall completeness, estimated from simulated quasars, is expected to be over 90%, whereas the overall efficiency (quasars/quasar candidates) is better than 65%. The selection algorithm targets ultraviolet excess quasars to i* = 19.1 and higher redshift (z ≳ 3) quasars to i* = 20.2, yielding approximately 18 candidates deg-2. In addition to selecting "normal" quasars, the design of the algorithm makes it sensitive to atypical AGNs such as broad absorption line quasars and heavily reddened quasars.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/75e28dd7a75751cb7bfd94c9220d126044bb04b8

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Citations in the corpus

Selection and Photometric Properties of K+A Galaxies (2003, methodology): “…and photometry (Lupton et al. 2001), calibration (Fukugita et al. 1996; Smith et al. 2002), spectroscopic target selection (Eisenstein et al. 2001; Strauss et al. 2002; Richards et al. 2002), and spectroscopic fiber placement (Blanton et al. 2003a) are performed with automated SDSS software.”
Average extinction curves and relative abundances for quasi-stellar object absorption-line systems at 1 ≤zabs < 2 (2006, background): “…in two ways: (a) via a set of rules relating to colour space for the purpose of reducing the number of false positives (e.g. white dwarfs, A stars) (Richards et al. 2002a) and (b) via the inclusion of all known X-ray and radio sources of SDSS objects (Anderson et al. 2003; Stoughton et al. 2002).”
Percolation Galaxy Groups and Clusters in the SDSS Redshift Survey: Identification, Catalogs, and the Multiplicity Function (2006, methodology): “Algorithms are applied to select spectroscopic targets for the main galaxy sample (Strauss et al. 2002), the luminous red galaxy sample (Eisenstein et al. 2001), and the quasar sample (Richards et al. 2002).”
The Broadband Optical Properties of Galaxies with Redshifts 0.02 < z < 0.22 (2002, neutral): “One of the goals is to spectroscopically observe 900,000 galaxies (down to rlim 17:77 mag), 100,000 luminous red galaxies (Eisenstein et al. 2001), and 100,000 quasars (Fan 1999; Richards et al. 2002).”
THE TENTH DATA RELEASE OF THE SLOAN DIGITAL SKY SURVEY: FIRST SPECTROSCOPIC DATA FROM THE SDSS-III APACHE POINT OBSERVATORY GALACTIC EVOLUTION EXPERIMENT (2013, background): “The SDSS-I/II quasar survey (Richards et al. 2002; Schneider et al. 2010) selects quasars at all redshifts and is flux-limited at magnitudes significantly brighter than BOSS; the bulk of the resulting quasar sample lies below z = 2.”
Spectral Energy Distributions and Multiwavelength Selection of Type 1 Quasars (2006, methodology): “We begin with SDSS type 1 quasars cataloged by Schneider et al. (2005), the majority of which were selected by the algorithm given by Richards et al. (2002).”
UNIFICATION OF LUMINOUS TYPE 1 QUASARS THROUGH C iv EMISSION (2010, methodology): “That said, our real fear in Richards et al. (2002a) was that, since the disk-wind model of Murray et al. (1995) produces a single-peaked C IV emission line through radiative transfer effects, such effects might also alter the symmetry of the line profile.”
THE ELEVENTH AND TWELFTH DATA RELEASES OF THE SLOAN DIGITAL SKY SURVEY: FINAL DATA FROM SDSS-III (2015, methodology): “…Physics Network, UK 4 the time the largest camera ever used in optical astronomy; Gunn et al. 1998) and spectroscopy of well-defined samples of galaxies (Strauss et al. 2002; Eisenstein et al. 2001) and quasars (Richards et al. 2002), using a 640- fiber pair of spectrographs (Smee et al. 2013).”
The Luminosity and Color Dependence of the Galaxy Correlation Function (2004, methodology): “…(Lupton et al. 2001), and photometric calibration (Hogg et al. 2001), and objects are then selected for spectroscopic follow-up using specific algorithms for the main galaxy sample (Strauss et al. 2002), luminous red galaxy sample (Eisenstein et al. 2001), and quasars (Richards et al. 2002).”
The Milky Way Tomography with SDSS. I. Stellar Number Density Distribution (2005, background): “The SDSS sample of spectroscopically confirmed quasars is flux-limited at i ¼ 19:1 (Richards et al. 2002 and references therein), and thus, it is not deep enough to assess the contamination level at the faint end relevant here.”
The Intrinsic Fraction of Broad Absorption Line Quasars (2008, methodology): “We therefore create a more homogenous QSO sample by retaining only those objects that were (or would have been) selected for spectroscopic follow-up by the final QSO targeting algorithm (as described by Richards et al. 2002).”
Very Small Scale Clustering and Merger Rate of Luminous Red Galaxies (2005, background): “…al. 2002; Pier et al. 2003), and good photometric calibration (Smith et al. 2002; Ivezić et al. 2004) allow one to select galaxies (Strauss et al. 2002; Eisenstein et al. 2001), quasars (Richards et al. 2002), and stars for spectroscopic observations with the twin fiber-fed double spectrographs.”
Galaxy bimodality versus stellar mass and environment (2006, background): “The main sets of targets are: (i) the main galaxy sample (MGS), an r < 17.77 selection (Strauss et al. 2002); (ii) luminous red galaxies (LRGs), an r < 19.5 and colour-selected galaxy sample (Eisenstein et al. 2001); and (iii) quasi-stellar objects (QSOs; Richards et al. 2002).”
A Catalog of Broad Absorption Line Quasars from the Sloan Digital Sky Survey Early Data Release (2003, background): “Vanden Berk et al. (2003) confirmed the findings of Richards et al. (2002), and also noted that the Baldwin Effect appears to evolve with redshift.”
QUASAR CLUSTERING FROM SDSS DR5: DEPENDENCES ON PHYSICAL PROPERTIES (2008, methodology): “…[2.0,2.5], [2.9,3.5], and [3.5,5.0], where we have deliberately avoided straddling two redshift deserts of quasars atz∼ 2.7 andz∼ 3.5, caused by the inefficiency of quasar color selection at these redshifts due to the contamination from F and GK stars (Fan 1999; Richards et al. 2002; see also fig.”
Galaxy Evolution from Halo Occupation Distribution Modeling of DEEP2 and SDSS Galaxy Clustering (2007, methodology): “Objects are selected for spectroscopic followup using specific algorithms for the main galaxy sample (Strauss et al. 2002), luminous red galaxy sample (Eisenstein et al. 2001), and quasars (Richards et al. 2002).”
The Linear Theory Power Spectrum from the Lyα Forest in the Sloan Digital Sky Survey (2004, methodology): “…which used 3300 Sloan Digital Sky Survey (SDSS) spectra from data releases one and two (Fukugita et al. 1996; Gunn et al. 1998; York et al. 2000; Hogg et al. 2001; Stoughton et al. 2002; Smith et al. 2002; Richards et al. 2002; Pier et al. 2003; Blanton et al. 2003; Abazajian et al. 2003, 2004).”
Double-peaked Low-Ionization Emission Lines in Active Galactic Nuclei (2003, neutral): “EMISSION LINES IN AGNs 1721 (Richards et al. 2002) and will obtain, upon completion, 105 AGN spectra with resolution of 1800–2100, covering the wavelength region 3800–9200 Å.”