The X-ray spectral properties of the AGN population in the XMM-Newton bright serendipitous survey

Context. X-ray surveys are a key instrument in the study of active galactic nuclei (AGN). Thanks to their penetrating ability, X-r ays are able to map the innermost regions close to the central super massive black hole (SMBH) as well as to detect and characterize its emission up to high redshift. Aims. We present here a detailed X-ray spectral analysis of the AGN belonging to the XMM-Newton bright survey (XBS). The XBS is composed of two flux-limited samples selected in the compl ementary 0.5-4.5 and 4.5-7.5 keV energy bands and comprising more than 300 AGN up to redshift∼ 2.4. Methods. We performed an X-ray analysis following two different approaches: by analyzing individually each AGN X-ray spectrum and by constructing average spectra for different AGN types. Results. From the individual analysis, we find that there seems to be an anti correlation between the spectral index and the sources’ hard X-ray luminosity, such that the average photon index for the higher luminosity sources (> 10 44 erg s −1 ) is significantly ( > 2�) flatter than the average for the lower luminosity sources. W e also find that the intrinsic column density distribution ag rees with AGN unified schemes, although a number of exceptions are found (3% of the whole sample), which are much more common among optically classified type 2 AGN. We also find that the so- called “soft-excess”, apart from the intrinsic absorption , constitutes the principal deviation from a power-law shape in AGN X-ray spectra and it clearly displays different characteristics, and likely a different origin, for unabsorbed and absorbed AGN. Regarding the shape of the average spectra, we find that it is best reproduc ed by . . .