X-ray Surveys and Wide-Field Optical/Near-Infrared Imaging with the Joint Dark Energy Mission

I briefly describe a few important scientific issues that could be addressed effectively via the combination of data from JDEM and X-ray missions. The topics covered are largely focused on active galactic nuclei (AGN) and include (1) the selection of AGN via X-ray emission and optical variability, (2) nuclear outbursts in galaxies due to transient fueling of their supermassive black holes, (3) moderate-luminosity AGN at high redshift (z > 4) found via application of "dropout" techniques to X-ray sources, and (4) the host-galaxy morphologies of X-ray selected AGN. I also describe the substantial challenges to obtaining wide-field X-ray data with sufficient sensitivity to complement JDEM properly.