2008/02/28 by Linhua Jiang, Xiaohui Fan, M. Vestergaard · 3 citations
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Luminosity #Nitrogen #OVV quasar #Physics #Quasar #Redshift #Sky #Spectral line #astro-ph
paper · pdf · doi:10.1086/587868
published as Astrophys.J.679:962-966,2008 · 8 pages, 4 figures; accepted by ApJ (ApJ June 10, 2008, v680 n1 issue)
arxiv created 2008/02/28 · openalex publication_date 2008/05/30 · arxiv updated 2009/12/01 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/05
We report on 293 quasars with strong N IV] λ1486 or N III] λ1750 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 Lyα and N V λ1240 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 N III]-rich quasars is 26% and in the N IV]-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.