Characterizing the Iron Kalpha Line Equivalent Width in Heavily Obscured AGN
Abstract
The fluorescent iron Kalpha emission line in the X-ray spectra of Active Galactic Nuclei (AGN) is thought to arise both from the accretion disk (resulting in the broad line component) and from the ‘torus’ of obscuring material further out (resulting in the narrow line component). A number of theoretical studies and observational results suggest that the equivalent width of the narrow line component increases with column density. Compton-thick sources, with NH>10^24cm^2, are thought to have iron Kalpha equivalent widths around 1keV or greater. However, there is considerable uncertainty, both in theory and in observation, for the details of the relationship between this equivalent width and column density. In this study we take advantage of the extremely deep Chandra Deep Field South 4Ms image and our STACKFAST stacking program to address this question. We report the trends we observe in equivalent width with column density. We also discuss the contamination rate we find for various Compton-thick AGN selection methods from the literature, using the stacked source iron line equivalent width as our barometer.
- Publication:
-
American Astronomical Society Meeting Abstracts #220
- Pub Date:
- May 2012
- Bibcode:
- 2012AAS...22033503T