The origin of N III λ990 and C III λ977 emission in AGN narrow-line region gas

J. W. Ferguson, G. J. Ferland, A. K. Pradhan

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


We discuss implications of HUT detections of C in λ977 and N III λ990 emission from the narrow-line region of the Seyfert 2 galaxy NGC 1068. In their discovery paper Kriss et al. showed that the unexpectedly great strength of these lines implies that the emitting gas must be shock-heated if the lines are collisionally excited. Here we investigate other processes which excite these lines in photoionization equilibrium. Recombination, mainly dielectronic, and continuum fluorescence are strong contributors to the line. The resulting intensities are sensitive to the velocity field of the emitting gas and require that the turbulence be of the same order of magnitude as the observed line width. We propose optical observations that will decide whether the gas is collisionally or radiatively heated.

Original languageEnglish
Pages (from-to)L55-L58
JournalAstrophysical Journal
Issue number2 PART 2
StatePublished - Jan 10 1995


  • Galaxies: individual (NGC 1068)
  • Galaxies: seyfert
  • ISM: atoms
  • Line: formation
  • Quasars: emission lines

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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