A sample of quasars with strong nitrogen emission lines from the sloan digital sky survey

Linhua Jiang, Xiaohui Fan, M. Vestergaard

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


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 Lya 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 m]-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.

Original languageEnglish (US)
Pages (from-to)962-966
Number of pages5
JournalAstrophysical Journal
Issue number2
StatePublished - Jun 1 2008


  • Galaxies: active
  • Quasars: emission lines
  • Quasars: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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