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Date and Time of the Query: 2019-04-20 T01:27:28 PDT
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For refcode 2001ApJ...549..155N:
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2001ApJ...549..155N Where is the[O III] {lambda}4363 Emitting Region in Active Galactic Nuclei? Tohru Nagao, Takashi Murayama, and Yoshiaki Taniguchi Received 2000 June 28; accepted 2000 November 2 ABSTRACT The emission-line flux ratio of [O III] {lambda}4363/[O III] {lambda}5007 (RO III) is a useful diagnostic for the ionization mechanism and physical properties of emission-line regions in active galactic nuclei (AGNs). However, it is known that simple photoionization models underpredict the [O III] {lambda}4363 intensity, being inconsistent with observations. In this paper we report on several pieces of evidence that a large fraction of the [O III] {lambda}4363 emission arises from the dense gas obscured by putative tori: (1) the visibility of high-RO III regions is correlated to that of broad-line regions, (2) higher RO III objects show hotter mid-infrared colors, (3) higher RO III objects show stronger highly ionized emission lines such as [Fe VII] {lambda}6087 and [Fe X] {lambda}6374, and (4) higher RO III objects have broader line width of [O III] {lambda}4363 normalized by that of [O III] {lambda}5007. To estimate how such a dense component contributes to the total emission-line flux, dual-component photoionization model calculations are performed. It is shown that the observed values of RO III of type 1 AGNs may be explained by introducing a 5%-20% contribution from the dense component, while those of type 2 AGNs may be explained by introducing a 0%-2% contribution. We also discuss the [O III] {lambda}4363 emitting regions in LINERs in the framework of our dual-component model. Subject headings: galaxies: active-galaxies: nuclei-galaxies: Seyfert- quasars: emission lines
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