Fe Kα Line in the Integrated Spectrum of Serendipitous 2XMM Catalog Sources

We exploited the 2XMM catalog and archival products to investigate the properties of the Fe Kα line at different redshifts. Individual source spectra are stacked in different redshift and luminosity bins over the range 0<z<=5. We report that the narrow Fe Kα line is significantly detected up to z = 2. We find compelling evidence for the `X-ray Baldwin effect' (decrease in the Fe Kα line strength with the increase in the X-ray luminosity) and no evolution of the average rest frame equivalent width of the Fe Kα line with redshift.