Query : 1997A&A...327..909B

1997A&A...327..909B - Astronomy and Astrophysics, volume 327, 909-920 (1997/11-3)

Photoionization of very high excitation gas in the Circinus galaxy and other active galactic nuclei.


Abstract (from CDS):

Recent measurements of the Circinus galaxy with ISO by Moorwood et al. (1996A&A...315L.109M) have confirmed the extremely high excitation of the emission-line spectrum in this active galaxy. Moorwood et al. modelled the spectrum in terms of photoionization of gas by a hard X-ray continuum plus a UV bump near 70eV. We present new photoionization calculations which differ markedly in geometry and in the adopted spectrum of the ionizing radiation. In our model, all the zones of high excitation coexist within the internal structure of matter-bounded clouds of 1pc thickness with a total cross section of 165pc2. A strong UV bump is not required to explain the line ratios in this picture. Our calculations consider the effects of radiation pressure exerted by photoelectric absorption which become very important at the high ionization parameters required by the line ratios. We propose that the radiation pressure generates a strong density gradient within the photoionized structure and is responsible for accelerating the matter-bounded gas, explaining the systematic blueshift observed for the coronal lines.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: Seyfert - line: formation - galaxies: ISM - galaxies: individual: Circinus galaxy

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 2MASX J03513577-2744345 Sy2 03 51 35.7643720392 -27 44 34.896912468   16.0       ~ 139 1
2 NGC 4151 Sy1 12 10 32.5759813872 +39 24 21.063527532   12.18 11.48     ~ 3524 2
3 NAME Circinus Galaxy Sy2 14 13 09.906 -65 20 20.47   10.89 9.84 10.6 10.0 ~ 1097 2

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