The properties of the fluorescence Fe K _ { \alpha } emission lines of a sample of 38 quasars ( QSOs ) observed with XMM–Newton are studied .
These objects are included in the optically selected sample from the Palomar–Green ( PG ) Bright Quasar Survey with an X–ray luminosity 1.3 \times 10 ^ { 43 } < L _ { 2 - 10 keV } < 5.1 \times 10 ^ { 45 } erg s ^ { -1 } and z \leq 1.72 .
For each object in the sample , we investigated the presence of both narrow and broad iron lines in detail .
A total of 20 out of the 38 QSOs show evidence of an Fe K _ { \alpha } emission line with a narrow profile .
The majority of the lines are consistent with an origin in low ionization material , which is likely to be located in the outer parts of the accretion disk , the molecular torus , and/or the Broad Line Region .
The average properties of the narrow Fe K _ { \alpha } emission line observed in the sample are similar to those of Seyfert type galaxies as inferred from recent XMM–Newton and Chandra studies .
A broad line has been significantly detected in only three objects .
Furthermore , we studied the relationship between the equivalent width ( EW ) of the iron line and the hard band X–ray luminosity for radio quiet quasars .
The analysis indicates that no clear correlation between the strength of the line and the hard X–ray luminosity is present , and our results do not show compelling evidence for an anticorrelation between these two quantities , i.e .
the so-called X–ray Baldwin effect .