XMM-Newton observations of 29 high redshift ( z > 2 ) quasars , including seven radio-quiet , 16 radio-loud and six Broad Absorption Line ( BAL ) objects , are presented ; due to the high redshifts , the rest-frame energy bands extend up to \sim 30–70 keV .
Over 2–10 keV , the quasars can be well fitted in each case by a simple power-law , with no strong evidence for iron emission lines .
The lack of iron lines is in agreement both with dilution by the radio jet emission ( for the radio-loud quasars ) and the X-ray Baldwin effect .
No Compton reflection humps at higher energies ( i.e. , above 10 keV in the rest frame ) are detected either .
Over the broad-band ( 0.3–10 keV ) , approximately half ( nine out of 16 ) of the radio-loud quasars are intrinsically absorbed , with the values of N _ { H } generally being 1–2 \times 10 ^ { 22 } cm ^ { -2 } in the rest frames of the objects .
None of the seven radio-quiet objects shows excess absorption , while four of the six BAL quasars are absorbed .
The radio-loud quasars have flatter continuum slopes than their radio-quiet counterparts ( \Gamma _ { RL } \sim 1.55 ; \Gamma _ { RQ } \sim 1.98 over 2–10 keV ) , while , after modelling the absorption , the underlying photon index for the six BAL quasars is formally consistent with the non-BAL radio-quiet objects .