A Sample of Quasars with Strong Nitrogen Emission Lines from the Sloan Digital Sky Survey

Abstract

We report on 293 quasars with strong NIV] lambda 1486 or NIII] lambda 1750 emission lines (rest-frame equivalent width > 3 Å) at 1.7 < z < 4.0 selected from the Sloan Digital Sky Survey (SDSS) Fifth Data Release. These nitrogen-rich (N-rich) objects comprise ~1.1% of the SDSS quasars. The comparison between the N-rich quasars and other quasars shows that the two quasar subsets share many common properties. We also confirm previous results that N-rich quasars have much stronger Lya and NV lambda 1240 emission lines. Strong nitrogen emission in all ionization states indicates high overall nitrogen abundances in these objects. We find evidence that the nitrogen abundance is closely related to quasar radio properties. The radio-loud fraction in the NIII]-rich quasars is 26% and in the NIV]-rich quasars is 69%, significantly higher than ~8% measured in other quasars with similar redshift and luminosity. Therefore, the high nitrogen abundance in N-rich quasars could be an indicator of a special quasar evolution stage, in which the radio activity is also strong.

arXiv comment8 pages, 4 figures; accepted by ApJ (ApJ June 10, 2008, v680 n1 issue)

References in corpus (14)

• Determining Central Black Hole Masses in Distant Active Galaxies and Quasars. II. Improved Optical and UV Scaling Relationships
• The cosmological evolution of quasar black-hole masses
• An Empirical Ultraviolet Template for Iron Emission in Quasars as Derived from I Zw 1
• Biases in Virial Black Hole Masses: An SDSS Perspective
• Elemental Abundances in QSOs: Star Formation and Galactic Nuclear Evolution at High Redshifts
• The Radio-Loud Fraction of Quasars is a Strong Function of Redshift and Optical Luminosity
• The Evolution of the Broad-Line Region among SDSS Quasars
• Metallicities and Abundance Ratios from Quasar Broad Emission Lines
• Radio galaxies at z~2.5: results from Keck spectropolarimetry
• High Redshift Quasars and Star Formation in the Early Universe
• Chemical Abundances in Broad Emission Line Regions: The "Nitrogen-Loud" QSO 0353-383
• Nitrogen Enriched Quasars in the Sloan Digital Sky Survey First Data Release
• Quasars with Super Metal Rich Emission Line Regions
• Discovery of Two Spectroscopically Peculiar, Low-Luminosity Quasars at z~4

Cited by in corpus (31)

• JADES NIRSpec Spectroscopy of GN-z11: Lyman-$\alpha$ emission and possible enhanced nitrogen abundance in a $z=10.60$ luminous galaxy
• The Sloan Digital Sky Survey Reverberation Mapping Project: Sample Characterization
• Nitrogen enhancements 440 Myr after the Big Bang: super-solar N/O, a tidal disruption event or a dense stellar cluster in GN-z11?
• The metallicity of the most distant quasars
• The Broad Absorption Line Tidal Disruption Event iPTF15af: Optical and Ultraviolet Evolution
• Candidate Type II Quasars at 2 < z < 4.3 in the Sloan Digital Sky Survey III
• Extreme N-emitters at high-redshift: signatures of supermassive stars and globular cluster or black hole formation in action?
• The Rest Frame Ultraviolet Spectra of UV-Selected Active Galactic Nuclei at z ~ 2-3
• Metallicity Diagnostics with Infrared Fine-Structure Lines
• An Ultraviolet Spectrum of the Tidal Disruption Flare ASASSN-14li
• Abundance Anomalies In Tidal Disruption Events
• The unusual NIV]-emitter galaxy GDS J033218.92-275302.7: star formation or AGN-driven winds from a massive galaxy at z=5.56
• Accretion onto Stars in the Disks of Active Galactic Nuclei
• Evidence of a tidal disruption event in GSN 069 from the abnormal carbon and nitrogen abundance ratio
• Distinguishing Tidal Disruption Events from Impostors
• Black Hole Masses of Intermediate-Redshift Quasars: Near Infrared Spectroscopy
• The Faint End of the Quasar Luminosity Function at z~4
• Metallicity in Quasar Broad Line Regions at Redshift $\sim$ 6
• Outflows from active galactic nuclei: The BLR-NLR metallicity correlation
• Rapid Black Hole Growth at the Dawn of the Universe: A Super-Eddington Quasar at z=6.6
• Carbon and Nitrogen Abundance Ratio In the Broad Line Region of Tidal Disruption Events
• High-redshift Extreme Variability Quasars from Sloan Digital Sky Survey Multi-Epoch Spectroscopy
• Evidence for Very Massive Stars in extremely UV-bright star-forming galaxies at $z\sim 2.2-3.6$
• Chemical enrichment and accretion of nitrogen-loud quasars
• Mapping the Outcomes of Stellar Evolution in the Disks of Active Galactic Nuclei
• Mg II and Fe II fluxes of luminous quasars at z ~ 2.7 and evaluation of the Baldwin effect in the flux-to-abundance conversion method for quasars
• A Candidate Tidal Disruption Event in a Quasar at z=2.359 from Abundance Ratio Variability
• Near-infrared spectroscopy of a nitrogen-loud quasar SDSS J1707+6443
• A Little Red Dot at $\mathbf{z}=7.3$ within a Large Galaxy Overdensity
• The Influence of Disk Composition on the Evolution of Stars in the Disks of Active Galactic Nuclei
• Insights into Quasar UV Spectra Using Unsupervised Clustering Analysis