X-ray Spectra of High Redshift openParz>4closePar Quasars

We propose to harness both the unequalled sensitivity and broad energy band ofXMM to systematically study a sample of high redshift (z>4) quasars, the mostluminous, youngest and least studies objects known. XMM can determine accuratelyboth the absorption column density and the underlying spectral shape of theXray emission allowing us to resolve intriguing, outstanding questions such as:Is the apparent difference between the Xray spectra of highredshift radioloudand radioquiet quasars real? If so, is it explained by intrinsic absorption orby different evolution of the Xray spectrum with redshift? What constraints canwe place on the Xray spectral evolution with redshift and/or luminosity foreach class? What limits can we put on intervening Damped Lyalpha systems? truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]