The hunt for Compton-thick AGN

We request 13ks XMM observations of 4 candidate Comptonthick AGN that we haveselected from the 22 month SwiftBAT survey on the basis of their flat Xrayspectra. Our principal purpose is to confirm the Comptonthick nature of theseAGN by searching for the strong 6.4keV iron line, and hence validate thecriteria that we used to find these rare objects. We will also search forsignatures of opticallythin scattering, constrain the size of the absorberthrough using via variability studies, and constrain the true Xray luminosityof the central engine and hence the impact of the obscuration on the numbercounts of Comptonthick sources in hard Xray surveys. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]