Deep Silicate Features in Compton-thick AGN Arise due to Dust in the Host Galaxy
Abstract
I will discuss the results of a recent study exploring the origins of mid-IR dust extinction in all bona-fide Compton-thick AGN using Spitzer-IRS spectroscopy. Unified AGN models predict that the dusty torus should produce strong silicate absorption features in heavily obscured systems; however, we find that only a minority of nearby Compton-thick AGN have strong Si-absorption features. Further, Compton-thick AGN hosted in low-inclination angle galaxies exhibit only a narrow-range in Si-absorption (S9.7∼0-0.3), which is consistent with that predicted by clumpy-torus models. On the basis of the IR spectra and additional lines of evidence, we conclude that the dominant contribution to the observed mid-IR dust extinction is dust located in the host galaxy (i.e., due to disturbed morphologies; dust-lanes; galaxy inclination angles) and not necessarily from a compact obscuring torus surrounding the central engine.
- Publication:
-
American Astronomical Society Meeting Abstracts #221
- Pub Date:
- January 2013
- Bibcode:
- 2013AAS...22120403G