Lineless Quasars at High Redshift: Extremely High Accretion Rate Sources

We propose to obtain XMMNewton spectroscopic imaging observations of aremarkable group of five quasars that lack detectable ultraviolet emission linesat z2.94.0 with a total exposure time of 195 ks. Obtaining virgul1000 photons persource, we will measure the hardXray photon index and intrinsic absorption,and search for an iron line and Compton reflection. Steep hardXray spectralslopes will indicate that high accretion rates may be responsible for theemissionline suppression with implications for the physics of the broadlineregion. The XMMNewton data may provide an important linkage between our sourcesand an apparently related group of radioquiet, weaklined active galacticnuclei at low redshift. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]