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Paper: The Quest for a Complete Census of AGN Activity
Volume: 381, The Second Annual Spitzer Science Center Conference: Infrared Diagnostics of Galaxy Evolution
Page: 383
Authors: Alexander, D.M.
Abstract: Deep X-ray surveys provide the most efficient identification of Active Galactic Nuclei (AGN) activity. However, recent evidence has indicated that the current < 10 keV surveys do not detect the most heavily obscured AGNs. Here we explore whether the X-ray undetected AGN population can be identified within the ultra-deep Spitzer survey of the GOODS-N field using X-ray stacking techniques. We find evidence for AGN activity in the Spitzer dataset and the strongest and hardest X-ray signal is produced by galaxies with starburst-like infrared spectral slopes and median properties of z ≈ 0.8 and LIR ≈ 1011 erg s−1. The stacked X-ray properties suggest that obscured AGN activity is present in these sources, with a median X-ray spectral slope of Γ ≈ 1 and LX ≈ 1042 erg s−1. These overall properties are consistent with the obscured AGN population expected to produce the unresolved X-ray background.
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