The Lockman-SpReSO Project: A Deep X-ray Spectral View of a FIR-selected AGN Population

We present a detailed X-ray spectral analysis of the active galactic nucleus (AGN) population in the Lockman-SpReSO project, a multiwavelength campaign of FIR sources in the Lockman Hole field. Using deep XMM-Newton observations cross-matched with FIR-selected galaxies, we characterize 94 AGNs based on their X-ray spectral properties. The sample is distributed over a large redshift range of z = 0.07-5, and reaches a flux limit of 5 times 10-16, erg, s-1, cm-2 in the 0.3-10, keV band. We model the X-ray spectra using absorbed power-law, reflection, and soft excess components to estimate intrinsic column densities (N H), rest-frame 2-10, keV luminosities, and iron line equivalent widths (EW). Additionally, we included an advanced model fitting for Compton-thick AGNs (CT-AGNs) using the XCLUMPY model. Our results show an increase in the fraction of obscured AGNs toward higher redshifts, including the identification of one strong and two borderline CT-AGN candidates with N H 10 24, cm-2. Soft excess emission is detected in 10 AGNs, with an average blackbody temperature of 0.12 plus or minus 0.02, keV. We also detect the X-ray Baldwin effect in both obscured and unobscured populations, and we found a strong correlation between the torus angular width (sigma tor), dust covering factor (f cov), and X-ray luminosity, described by f cov = (-0.1 plus or minus 0.01) times (L 2-10, keV/(10 44, erg, s-1)) + (0.65 plus or minus 0.01), supporting the receding torus scenario. While consistent with deep X-ray surveys, the FIR selection favours the identification of dusty star-forming host galaxies and heavily obscured AGNs.