Latest Results from the XMM-SERVS X-ray Survey of the LSST Deep-Drilling Fields

Cosmic X-ray surveys over the past two decades have played a critical role in transforming our understanding of growing supermassive black holes (SMBHs) in the distant universe. I will describe new results from one key survey advancing this effort: the 13.1 deg² XMM-SERVS survey. XMM-SERVS has successfully mapped three LSST Deep-Drilling Fields (DDFs) at 50 ks XMM-Newton depth, focusing on the SERVS areas of W-CDF-S, XMM-LSS, and ELAIS-S1. These fields have first-rate multiwavelength coverage already and are LSST/DES DDFs, MOONS/PFS/4MOST massive spectroscopy fields, prime TolTEC/ALMA fields, and SDSS-V/4MOST multi-object reverberation-mapping fields. About 12,000 X-ray sources have been detected and characterized, the majority of which (86%) are active galactic nuclei (AGNs), and these are presently being studied. I will summarize science investigations including multiwavelength fitting of infrared-to-X-ray spectral energy distributions, identification of the most highly X-ray obscured AGNs, dwarf AGN studies, combined radio/X-ray AGN investigations, and mapping of cosmic SMBH growth as a function of galaxy stellar mass. I will also briefly highlight how the proposed STAR-X MIDEX mission could obtain much more sensitive X-ray coverage of the LSST DDFs as it conducts its 12 deg² Deep and 300 deg² Medium-Deep time-domain surveys.