I present a review of X-ray and mid-IR surveys for Compton-thick Active Galactic Nuclei (AGN). These are the most highly obscured sources having hydrogen column densities >1.5x10^24 cm-2. Key surveys in the local Universe are presented including the high energy SWIFT/BAT and INTEGRAL surveys, mid-IR and also optical surveys. Recently, deep X-ray surveys with Chandra and XMM-Newton have produced a number of candidate Compton-thick AGN at higher redshift primarily in the Chandra Deep Field South region. In addition, mid-IR surveys with Spitzer have helped to develop novel complementary techniques for the selection of Compton-thick AGN. The mid-IR techniques used to identify Compton-thick AGN include: a) 24 micron excess sources relative to their optical emission b) Spitzer spectroscopy for the detection of high optical depth Si 9.7 micron absorption features c) low X-ray to 6 micron luminosity ratio.
@article{arxiv.1204.2173,
title = {Recent developments in the search for Compton-thick AGN},
author = {I. Georgantopoulos},
journal= {arXiv preprint arXiv:1204.2173},
year = {2015}
}
Comments
to appear in 'International Journal of Modern Physics D', Invited talk in the Third Galileo - Xu Guangqi meeting, Beijing, China, October 11-15 2011