Improved redshifts for SDSS quasar spectra

Abstract

A systematic investigation of the relationship between different redshift estimation schemes for more than 91000 quasars in the Sloan Digital Sky Survey (SDSS) Data Release 6 (DR6) is presented. The publicly available SDSS quasar redshifts are shown to possess systematic biases of Dz/(1+z)>=0.002 (600km/s) over both small (dz~0.1) and large (dz~1) redshift intervals. Empirical relationships between redshifts based on i) CaII H & K host galaxy absorption, ii) quasar [OII] 3728, iii) [OIII] 4960,5008 emission, and iv) cross-correlation (with a master quasar template) that includes, at increasing quasar redshift, the prominent MgII 2799, CIII] 1908 and CIV 1549 emission lines, are established as a function of quasar redshift and luminosity. New redshifts in the resulting catalogue possess systematic biases a factor of ~20 lower compared to the SDSS redshift values; systematic effects are reduced to the level of Dz/(1+z)<10^-4 (30km/s) per unit redshift, or <2.5x10^-5 per unit absolute magnitude. Redshift errors, including components due both to internal reproducibility and the intrinsic quasar-to-quasar variation among the population, are available for all quasars in the catalogue. The improved redshifts and their associated errors have wide applicability in areas such as quasar absorption outflows, quasar clustering, quasar-galaxy clustering and proximity-effect determinations.

Accepted to MNRAS. The QSO redshift catalogue and QSO template spectrum can be downloaded from ftp://ftp.ast.cam.ac.uk/pub/phewett/ until 1st May 2010

References in corpus (7)

• The Sloan Digital Sky Survey Quasar Catalog IV. Fifth Data Release
• A Catalog of Broad Absorption Line Quasars in Sloan Digital Sky Survey Data Release 5
• Clustering of High Redshift ($z\ge 2.9$) Quasars from the Sloan Digital Sky Survey
• Narrow associated QSO absorbers: clustering, outflows and the line-of-sight proximity effect
• The Quasar-frame Velocity Distribution of Narrow CIV Absorbers
• The transverse proximity effect in the z ~ 2 Lyman-alpha forest suggests QSO episodic lifetimes of ~1 Myr
• Average Properties of a Large Sample of z_abs ~ z_em associated Mg II Absorption Line Systems

Cited by in corpus (197)

• A Catalog of Quasar Properties from SDSS DR7
• Spectral Classification and Redshift Measurement for the SDSS-III Baryon Oscillation Spectroscopic Survey
• Active Galactic Nuclei: what's in a name?
• The Sloan Digital Sky Survey Quasar Catalog: Sixteenth Data Release
• Unification of Luminous Type 1 Quasars through CIV Emission
• H0LiCOW I. $H_0$ Lenses in COSMOGRAIL's Wellspring: Program Overview
• Physical properties of 15 quasars at $z\gtrsim 6.5$
• Ubiquitous giant Ly $\alpha$ nebulae around the brightest quasars at $z\sim 3.5$ revealed with MUSE
• Comparing Single-Epoch Virial Black Hole Mass Estimators for Luminous Quasars
• MOJAVE XIII. Parsec-Scale AGN Jet Kinematics Analysis Based on 19 years of VLBA Observations at 15 GHz
• The tight relation between X-ray and ultraviolet luminosity of quasars
• Black hole mass estimates and emission-line properties of a sample of redshift z>6.5 quasars
• The SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Quasar Target Selection
• Bright [CII] and dust emission in three z>6.6 quasar host galaxies observed by ALMA
• Correcting CIV-Based Virial Black Hole Masses
• A Catalog of Quasar Properties from Sloan Digital Sky Survey Data Release 16
• Gemini GNIRS near-infrared spectroscopy of 50 quasars at z>~5.7
• The JHU-SDSS metal absorption line catalog: redshift evolution and properties of Mg II absorbers
• The Sloan Digital Sky Survey Reverberation Mapping Project: Velocity Shifts of Quasar Emission Lines
• Extragalactic Peaked-Spectrum Radio Sources at Low Frequencies
• QSO MUSEUM I: A sample of 61 extended Ly$\alpha$-emission nebulae surrounding $z\sim 3$ quasars
• Detection of atomic carbon [CII] 158 micron and dust emission from a z=7.1 quasar host galaxy
• The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample: measurement of the growth rate of structure from the anisotropic correlation function between redshift 0.8 and 2.2
• Active galactic nuclei at z~1.5: II. Black Hole Mass estimation by means of broad emission lines
• Quasars Probing Quasars VI. Excess HI Absorption Within One Proper Mpc of z~2 Quasars
• Broad Absorption Line Disappearance on Multi-Year Timescales in a Large Quasar Sample
• Major contributor to AGN feedback: VLT X-shooter observations of SIV BAL QSO outflows
• ALMA Observations Show Major Mergers Among the Host Galaxies of Fast-growing, High-redshift Supermassive Black Holes
• CIV Emission Line Properties and Systematic Trends in Quasar Black Hole Mass Estimates
• Extremely Red Quasars in BOSS
• Lyα emission line reconstruction for high-$z$ QSOs
• The large-scale Quasar-Lyman α Forest Cross-Correlation from BOSS
• The X-shooter/ALMA Sample of Quasars in the Epoch of Reionization. II. Black Hole Masses, Eddington Ratios, and the Formation of the First Quasars
• The X-SHOOTER/ALMA sample of Quasars in the Epoch of Reionization. I. NIR spectral modeling, iron enrichment and broad emission line properties
• BAL and non-BAL quasars: continuum, emission and absorption properties establish a common parent sample
• The Faint End of the z=5 Quasar Luminosity Function from the CFHTLS
• Constraining Sub-Parsec Binary Supermassive Black Holes in Quasars with Multi-Epoch Spectroscopy. II. The Population with Kinematically Offset Broad Balmer Emission Lines
• SuperRAENN: A Semi-supervised Supernova Photometric Classification Pipeline Trained on Pan-STARRS1 Medium Deep Survey Supernovae
• The DESI Survey Validation: Results from Visual Inspection of the Quasar Survey Spectra
• ERQs are the BOSS of Quasar Samples: The Highest-Velocity [OIII] Quasar Outflows
• X-ray and Multiwavelength Insights into the Nature of Weak Emission-Line Quasars at Low Redshift
• MUSE searches for galaxies near very metal-poor gas clouds at z~3: new constraints for cold accretion models
• Rest-frame Optical Properties of Luminous 1.5<z<3.5 Quasars: the Hbeta-[OIII] Region
• Mean-flux Regulated PCA Continuum Fitting of SDSS Lyman-alpha Forest Spectra
• The Cosmic Ultraviolet Baryon Survey (CUBS) I. Overview and the diverse environments of Lyman limit systems at z<1
• Multi-wavelength and neutrino emission from blazar PKS 1502+106
• Precious Metals in SDSS Quasar Spectra I: Tracking the Evolution of Strong, 1.5 < z < 4.5 CIV Absorbers with Thousands of Systems
• Detection of Rest-frame Optical Lines from X-shooter Spectroscopy of Weak Emission Line Quasars
• $HST$ Grism Confirmation of $16$ Structures at $1.4<z<2.8$ from the Clusters Around Radio-Loud AGN (CARLA) Survey
• Bayesian High-Redshift Quasar Classification from Optical and Mid-IR Photometry
• Compact Symmetric Objects and Supermassive Binary Black Holes in the VLBA Imaging and Polarimetry Survey
• Patterns in the multi-wavelength behavior of candidate neutrino blazars
• RoboPol: Do optical polarization rotations occur in all blazars?
• Cosmic Evolution of Black Holes and Spheroids. V. The Relation Between Black Hole Mass and Host Galaxy Luminosity for a Sample of 79 Active Galaxies
• Mapping the Lyman-Alpha Emission Around a z~6.6 QSO with MUSE: Extended Emission and a Companion at Close Separation
• Reionization history constraints from neural network based predictions of high-redshift quasar continua
• The correlations between optical/UV broad lines and X-ray emission for a large sample of quasars
• BAL phosphorus abundance and evidence for immense ionic column densities in quasar outflows: VLT X-Shooter observations of quasar SDSS J1512+1119
• Connecting the X-ray properties of weak-line and typical quasars: testing for a geometrically thick accretion disk
• Kiloparsec-scale jets in three radio-loud narrow-line Seyfert 1 galaxies
• Performance of the Quasar Spectral Templates for the Dark Energy Spectroscopic Instrument
• Search for a drifting proton--electron mass ratio from H${}_2$
• Black hole mass estimation for Active Galactic Nuclei from a new angle
• The Dependence of C IV Broad Absorption Line Properties on Accompanying Si IV and Al III Absorption: Relating Quasar-Wind Ionization Levels, Kinematics, and Column Densities
• Low-Ionization Outflows in High Eddington Ratio Quasars
• Multi-wavelength view of the close-by GRB 190829A sheds light on gamma-ray burst physics
• Mean and Extreme Radio Properties of Quasars and the Origin of Radio Emission
• A comparison of quasar emission reconstruction techniques for $z\ge 5.0$ Lyman-$\alpha$ and Lyman-$\beta$ transmission
• No signs of star formation being regulated in the most luminous quasars at z~2 with ALMA
• An X-ray and Multiwavelength Survey of Highly Radio-Loud Quasars at z > 4: Jet-Linked Emission in the Brightest Radio Beacons of the Early Universe
• Testing AGN outflow and accretion models with CIV and HeII emission line demographics in z=2 quasars
• Dusty Tori of Luminous Type 1 Quasars at z \sim 2
• Andromeda's Parachute: A Bright Quadruply Lensed Quasar at z=2.377
• Refining the associations of the Fermi Large Area Telescope Source Catalogs
• Chemical abundances of damped Lyman alpha systems in the XQ-100 survey
• Statistical Properties of Multi-epoch Spectral Variability of SDSS Stripe82 Quasars
• Identification of Outflows and Candidate Dual Active Galactic Nuclei in SDSS Quasars at z=0.8-1.6
• The z=0.54 LoBAL Quasar SDSS J085053.12+445122.5: I. Spectral Synthesis Analysis Reveals a Massive Outflow
• On the link between associated MgII absorbers and star formation in quasar hosts
• A Giant Metrewave Radio Telescope search for associated H{\sc i} 21\,cm absorption in GHz-peaked-spectrum sources
• Classification of Broad Absorption Line Quasars with a Convolutional Neural Network
• The James Webb Space Telescope North Ecliptic Pole Time-Domain Field -- I: Field Selection of a JWST Community Field for Time-Domain Studies
• Astrometric Limits on the Stochastic Gravitational Wave Background
• The rocky road to quiescence: compaction and quenching of quasar host galaxies at z~2
• HST Grism Confirmation of Two $z\sim 2$ Structures from the Clusters Around Radio-Loud AGN (CARLA) Survey
• Search for anisotropic Lorentz invariance violation with γ-rays
• The Physical Properties of Low Redshift FeLoBAL Quasars. I. Spectral Synthesis Analysis of the BAL Outflows using $SimBAL$
• Sensitive Chandra coverage of a representative sample of weak-line quasars: revealing the full range of X-ray properties
• A Comparison of Cosmological Models Using Strong Gravitational Lensing Galaxies
• Active Galactic Nucleus Environments and Feedback to Neighboring Galaxies at $z\sim 5$ Probed by Lyman-Alpha Emitters
• ALMA Observations of Quasar Host Galaxies at $z\simeq 4.8$
• A Comparison of Cosmological Models Using Time Delay Lenses
• The WISE-2MASS Survey: Red Quasars Into the Radio Quiet Regime
• The Redshifted Hydrogen Balmer and Metastable He I Absorption Line System in Mini-FeLoBAL Quasar SDSS J112526.12+002901.3: A Parsec Scale Accretion Inflow?
• HST-COS Observations of AGNs. III. Spectral Constraints in the Lyman Continuum from Composite COS/G140L Data
• The Time-Domain Spectroscopic Survey: Target Selection for Repeat Spectroscopy
• Near-IR spectroscopy of luminous LoBAL quasars at 1<z<2.5
• Discovery of the Transition of a Mini-Broad Absorption Line into Broad Absorption in the SDSS Quasar J115122.14+020426.3
• The COS Absorption Survey of Baryon Harbors: The Galaxy Database and Cross-Correlation Analysis of OVI Systems
• Locating the gamma-ray emission region in the brightest Fermi-LAT Flat Spectrum Radio Quasars
• HST and Ground-Based Spectroscopy of Quasar Outflows: From Mini-BALs to BALs
• Survey of Extremely High-velocity Outflows in Sloan Digital Sky Survey Quasars
• Quasars Probing Quasars IX. The Kinematics of the Circumgalactic Medium Surrounding z ~ 2 Quasars
• A successful search for intervening 21 cm HI absorption in galaxies at 0.4 < z <1.0 with the Australian Square Kilometre Array Pathfinder (ASKAP)
• Metallicity and Quasar Outflows
• Characterizing Quasar CIV Emission-line Measurements from Time-resolved Spectroscopy
• Photometric Classification of 2315 Pan-STARRS1 Supernovae with Superphot
• 2FGL J0846.0+2820: A new neutron star binary with a giant secondary and variable $\gamma$-ray emission
• Placing High-Redshift Quasars in Perspective: a Catalog of Spectroscopic Properties from the Gemini Near Infrared Spectrograph -- Distant Quasar Survey
• Evidence for higher black hole spin in radio-loud quasars
• Dating individual quasars with the HeII proximity effect
• Detection of Two Intervening Ne VIII Absorbers Probing Warm Gas at z~0.6
• Unshifted Metastable He I* Mini-Broad Absorption Line System in the Narrow Line Type 1 Quasar SDSS J080248.18$+$551328.9
• Variability of Low-ionization Broad Absorption Line Quasars Based on Multi-epoch Spectra from The Sloan Digital Sky Survey
• Feeding the Accretion Disk from the Dusty Torus in a Reddened Quasar
• An Apparent Redshift Dependence of Quasar Continuum: Implication for Cosmic Dust Extinction?
• The candidate cluster and protocluster catalog (CCPC) of spectroscopically identified structures spanning $2.74<z<3.71$
• The Blueshift Of Civ Broad Emission Line In Qsos
• Directly tracing cool filamentary accretion over >100 kpc into the interstellar medium of a quasar host at z=1
• Evidence that Emission and Absorption Outflows in Quasars Are Related
• Exploring the Morphology and Origins of the 4C 38.41 Jet
• Outflow and hot dust emission in high redshift quasars
• Exploring the Variability of the Flat Spectrum Radio Source 1633+382. I. Phenomenology of the Light Curves
• The $\text{Chandra}$ 3CR extragalactic survey at high redshift
• Relativistic redshifts in quasar broad lines
• The correlated variations of C IV narrow absorption lines and quasar continuum
• Quasars probing quasars X: The quasar pair spectral database
• Deceleration of CIV and SiIV broad absorption lines in X-ray bright quasar SDSS-J092345+512710
• Broad absorption line disappearance/emergence in multiple ions in a weak emission-line quasar
• A Rapid and Large-Amplitude X-ray Dimming Event in a z ~ 2.6 Radio-Quiet Quasar
• Radio Jet Proper-motion Analysis of Nine Distant Quasars above Redshift 3.5
• Correlation between optical flux and polarization variations in Flat Spectrum Radio Quasars on diverse timescales
• Appearance vs Disappearance of broad absorption line troughs in quasars
• Exploring the Variability of the Flat Spectrum Radio Source 1633+382. II: Physical Properties
• A hot gaseous galaxy halo candidate with Mg X absorption
• Vanishing Absorption and Blueshifted Emission in FeLoBAL Quasars
• Using the Properties of Broad Absorption Line Quasars to Illuminate Quasar Structure
• Probing the environment of high-z quasars using the proximity effect in projected quasar pairs
• Disappearance of a narrow Mg II absorption system with a measured velocity up to $166,000km{\mathrm{s}}^{-1}$
• Galactic Winds across the Gas-Rich Merger Sequence: I. Highly Ionized N V and O VI Outflows in the QUEST Quasars
• Narrow, Intrinsic CIV Absorption in Quasars as it Relates to Outflows, Orientation, and Radio Properties
• The luminosity dependence of quasar UV continuum slope: dust extinction scenario
• Connecting Low- and High-Redshift Weak Emission-Line Quasars via HST Spectroscopy of Ly$\alpha$ Emission
• Correlated time variability of multi-component high velocity outflows in J162122.54+075808.4
• The detection of possible transient Quasi-Periodic Oscillations in the $\gamma$-ray light curve of PKS 0244-470 and 4C+38.41
• Correlated orientations of the axes of large quasar groups on Gpc scales
• Prescriptions for Correcting Ultraviolet-Based Redshifts for Luminous Quasars at High Redshift
• Broadband study of OQ 334 during its flaring state
• Collective properties of quasar narrow associated absorption lines
• The Sloan Digital Sky Survey Reverberation Mapping Project: Biases in z>1.46 Redshifts due to Quasar Diversity
• No redshift evolution in the rest-frame UV emission line properties of quasars from z=1.5 to z=4.0
• Gemini Near Infrared Spectrograph -- Distant Quasar Survey: Augmented Spectroscopic Catalog and a Prescription for Correcting UV-Based Quasar Redshifts
• Reddening and He I* $\lambda 10830$ Absorption Lines in Three Narrow-line Seyfert 1 Galaxies
• [OIII] emission in z=2 quasars with and without Broad Absorption Lines
• Correlation between the ionizing continuum and variable C iv broad absorption line in multi-epoch observations of SDSS J141007.74+541203.3
• Physical Conditions of Five O VI Absorption Systems Towards PG $1522+101$
• Temporal variability and estimation of jet parameters for Ton 599
• Time variability of ultra-fast BAL outflows using SALT: C IV equivalent width analysis
• Outflow and metallicity in the broad-line region of low-redshift active galactic nuclei
• Emission Line Variability during a Nonthermal Outburst in the Gamma-Ray Bright Quasar 1156+295
• Intranight Optical Variability of Radio-Quiet Weak Emission Line Quasars-IV
• How to Detect Inclined Water Maser Disks (and Possibly Measure Black Hole Masses)
• Narrow C IV absorption doublets on quasar spectra of the Baryon Oscillation Spectroscopic Survey
• The Study of Circumgalactic Medium with Quasar Pairs
• Catching profound optical flares in blazars
• Coordinated time variability of multi-phase ultra-fast outflows in J132216.25+052446.3
• The Most Compact Bright Radio-loud AGN -- II. VLBA Observations of Ten Sources at 43 and 86~GHz
• Ghostly Damped Ly$\alpha$ Systems: Tracers of Gas Flows in the Close Vicinity of Quasars ?
• Modeling Lyman-α Forest Cross-Correlations with LyMAS
• The disappearance of a narrow Mg II absorption system in quasar SDSS J165501.31+260517.4
• The Host Galaxy of the Recoiling Black Hole Candidate in 3C 186: An Old Major Merger Remnant at the Center of a z=1 Cluster
• The Nature of Luminous Quasars with Very Large C IV Equivalent Widths
• Nature and Origins of Rich Complexes of C IV Associated Absorption Lines
• The dust, nebular emission and dependence on QSO radio properties of the associated Mg II absorption line systems
• Galaxy Spectra Networks (GaSNet). III. Generative pre-trained network for spectrum reconstruction, redshift estimate and anomaly detection
• Modeling the Spectral Diversity of Quasars in the Sixteenth Data Release from the Sloan Digital Sky Survey
• Determining Quasar Orientation
• $\text{Fermi}$-LAT realtime follow-ups of high-energy neutrino alerts
• Insights into Quasar UV Spectra Using Unsupervised Clustering Analysis
• The physical constraints on a new LoBAL QSO at z=4.82
• Constraints on the Inner Regions of Lensing Galaxies from Central Images using a Recent AGN Offset Distribution
• Search for anomalous features in gamma-ray blazar spectra corrected for the absorption on the extragalactic background light
• The Seventeenth Data Release of the Sloan Digital Sky Surveys: Complete Release of MaNGA, MaStar and APOGEE-2 Data
• X-ray selected broad absorption line quasars in SDSS-V: BALs and non-BALs span the same range of X-ray properties
• A Novel Test of Quasar Orientation
• Incidence of Strong MgII Absorbers Towards Different Types of Quasars
• X-ray properties of high-redshift Radio Loud and Radio Quiet Quasars observed by Chandra
• Spectral Signatures of Quasar Ages at z~3
• Automated Measurement of Quasar Redshift with a Gaussian Process
• A Redshift Survey of the Coma Cluster (A1656): Understanding the Nature of Subhalos in the Weak-lensing Map
• A broad-line quasar with unexplained extreme velocity offsets: post-shock outflow?
• First detection of VHE gamma-ray signal from the FSRQ TON 0599
• Multi-band optical variability of the blazar OP 313 in the outburst state during 2024-2025
• VLBI properties of compact interplanetary scintillators detected by the Murchison Widefield Array
• Circumgalactic medium of quasar host galaxies at 0.4<z<0.8 probed by strong Mg II absorption
• Metal-strong Inflows at the Outer-galactic-scale of a Quasar
• The dependence of the fraction of radio luminous quasars on redshift and its theoretical implications