Compton Shoulder Diagnostics in Active Galactic Nuclei for Probing the Metallicity of the Obscuring Compton-thick Tori
Abstract
We analyzed the spectral shape of the Compton shoulder around the neutral Fe-K α 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 α line core intensity are powerful diagnostics tools for analyzing the structure of the molecular tori, which obscures 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 independently, using only the spectral data only around the Fe-K α emission line. The obtained column density and inclination angle are consistent with 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}-0.17+0.19 and 1.74 ± 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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2018
- DOI:
- 10.3847/1538-4357/aae1fe
- arXiv:
- arXiv:1810.01088
- Bibcode:
- 2018ApJ...867...80H
- Keywords:
-
- galaxies: active;
- galaxies: individual: Circinus;
- galaxies: nuclei;
- galaxies: Seyfert;
- techniques: spectroscopic;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 8 pages, 3 figures, 1 table, accepted for publication in The Astrophysical Journal