Weak Line Quasars at High Redshift: Extremely High Accretion Rate Sources

The Sloan Digital Sky Survey has recently discovered a remarkable group of virgul80quasars at z2.25.9 with extremely weak emission lines in their restframe UVspectra. We propose to extend our XMMNewton observations of such sources andobtain imaging spectroscopy of four quasars of this class with a total exposuretime of 165 ks, providing virgul1000 photons per source. This will enable an accuratemeasurement of the hardXray photon index required for a robust determinationof the accretion rate in each source. Steep spectral slopes will indicate thathigh accretion rates may be responsible for the intrinsic weakness of the UVemission lines. The proposed observations will lead to new insights about theaccretion process and broad emission line formation in all active galactic nuclei. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]