X-ray-to-infrared spectral energy distributions and source properties in the XMM-SERVS fields

The XMM-SERVS survey is a recently finished, medium-deep X-ray survey covering 13 deg² in three fields (i.e., XMM-LSS, W-CDF-S, and ELAIS-S1) with extensive multi-wavelength coverage, and these fields will also be Rubin LSST Deep-Drilling Fields. This survey, together with the archival data in these fields, has 5.4 Ms of flare-filtered XMM-Newton exposure in total and has detected around 12,000 X-ray sources, including around 10,000 active galactic nuclei (AGNs). To characterize sources in these fields, we first refined the optical-to-infrared photometry and photometric redshifts and then analyzed the X-ray-to-FIR (far-infrared) spectral energy distributions (SEDs) with CIGALE, which allows explicit treatment of X-ray emission to constrain AGN contributions to the SED. We probed the selection of AGNs aside from the X-ray selection and carefully calibrated the SED selection of AGN candidates using the embedded CDF-S survey results. We decomposed the SEDs into the galaxy and AGN components and measured the host-galaxy properties (e.g., stellar mass and star-formation rate). The SED-fitting results are compared with several previous measurements, which, however, are limited to a small number of sources, to perform external calibrations. Our catalog provides source properties for the largest sample reaching a similar X-ray depth and will help probe the black-hole growth over cosmic time in the near future.