TY - JOUR
T1 - The origin of N III λ990 and C III λ977 emission in AGN narrow-line region gas
AU - Ferguson, J. W.
AU - Ferland, G. J.
AU - Pradhan, A. K.
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 1995/1/10
Y1 - 1995/1/10
N2 - 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.
AB - 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.
KW - Galaxies: individual (NGC 1068)
KW - Galaxies: seyfert
KW - ISM: atoms
KW - Line: formation
KW - Quasars: emission lines
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U2 - 10.1086/187714
DO - 10.1086/187714
M3 - Article
AN - SCOPUS:11944264457
SN - 0004-637X
VL - 438
SP - L55-L58
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2 PART 2
ER -