http://arxiv.org/abs/1810.01088
We analyzed the spectral shape of the Compton shoulder around the neutral Fe-K$\alpha$ line of the Compton-thick type II Seyfert nucleus of the Circinus galaxy. The characteristics of this Compton shoulder with respect to the reflected continuum and Fe-K$\alpha$ line core intensity are a powerful diagnostics tool for analyzing the structure of the molecular tori, which obscure the central engine. We applied our Monte-Carlo-based X-ray reflection spectral model to the Chandra High Energy Transmission Grating data and successfully constrained the various spectral parameters %the hydrogen column density, the inclination angle, and %the metal abundance, independently, using only the spectral data only around the Fe-K$\alpha$ emission line. The obtained column density and inclination angle are consistent with the previous observations and the Compton-thick type II Seyfert picture. In addition, we determined the metal abundance of the molecular torus for the case of the smooth and clumpy torus to be 1.75$^{+0.19}{-0.17}$ and 1.74$\pm$0.16 solar abundance, respectively. Such slightly over-solar abundance can be useful information for discussing the star formation rate in the molecular tori of active galactic nuclei.
M. Hikitani, M. Ohno, Y. Fukazawa, et. al.
Wed, 3 Oct 18
7/64
Comments: 8 pages, 3 figures, 1 table, accepted for publication in The Astrophysical Journal
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