091307

The primary X-ray emission observed in AGN is believed to be produced from a tiny region surrounding the SMBH namely the corona. A critical coronal compactness versus temperature threshold is predicted above which any increase in the source luminosity would then generate positron-electron pairs rather than continue heating the coronal plasma. Current observations show that all local AGNs populate the region below this critical line. However these models have rarely been probed in the high-luminosity regime where the tightest constraints can be made on the coronal models. Here we propose four high-luminosity quasars (zvirgul1-2) to more than double the current sample size of high-luminosity quasars to further constrain the coronal models and thus better understand the physics of coronae. [truncated! Please see actual data for full text]