Obscured Quasars and the Need for Optical to NIR, Massively Multiplexed, Spectroscopic Facilities

Most bulge-dominated galaxies host black holes with masses that tightly correlate with the masses of their bulges, which could mean that black holes may regulate galaxy growth or vice versa or that they may grow in lock-step. The quest to understand how, when, and where those black holes formed motivates much of extragalactic astronomy. Here we focus on a population of galaxies with active black holes in their nuclei (active galactic nuclei or AGN) hidden by dust and gas: the emission from the broad-line region is either entirely or partially obscured with a visual extinction of 1 or above. Though not yet precise, this limit appears to be the point at which the populations of AGN may evolve differently. We present FIR spectroscopic observations with SOFIA of a sample of nearby, narrow line AGN and discuss the need to study the impacts of the AGN on the multi-phase ISM and the relevance to cosmic-noon objects. Modern wide-field imaging surveys performed by Roman Space Telescope and Vera Rubin Observatory’s Large Synoptic Survey will open a new window on the Universe, enabling the discovery and study of AGN hosts too faint to be studied previously. To realize the full scientific potential of these surveys, we must examine those objects using spectroscopic techniques. Specifically, we will need large multiplexed spectroscopic instruments to perform dedicated surveys in the optical and NIR to pin down the demographics of such objects and study their reddening properties, star-formation histories, and excitation conditions. These critical studies will shed light on the role of black holes in galaxy evolution during the epoch of peak growth activity.