Dancers in the Dark: Obscured Active Galactic Nuclei across Time

With extraordinary survey speeds and optical to near-infrared wavelength coverage in imaging and spectroscopic modes, Roman is poised to make impressive strides in understanding of general astrophysics problems like how, why, and when galaxies grow super-massive black holes, form stars, and stop forming stars. Of particular interest is the population of galaxies with active black holes in their nuclei (active galactic nuclei or AGN) that are fully or partially hidden by dust and gas, as those AGN may evolve differently than non-obscured AGN. Several X-ray through Radio imaging missions are geared to detect on the order of 10^5 obscured AGN. To realize the full scientific potential of these surveys, we must examine those objects using spectroscopic techniques to study their reddening properties, star- formation histories, and excitation conditions. With massively multiplexed spectroscopic facilities, we can efficiently measure ionized and hot molecular gas emission lines, probing star formation, AGN feedback, and gas flows in and between galaxies and the circum-galactic medium. These critical studies will shed light on the role of black holes in galaxy evolution during the epoch of peak growth activity.