Quantifying Selection Effects in Deep-Field AGN Surveys with BASS

Deep extragalactic surveys with Chandra and XMM-Newton have led to the discovery of thousands of active galactic nuclei (AGN), resolution of much of the cosmic X-ray background below 10 keV, and impactful studies on black hole growth and AGN host galaxies. However, these surveys are biased against obscured AGN, particularly those that are Compton-thick (NH ≥ 10²⁴ cm^-2). Meanwhile, the Swift-BAT all-sky survey has detected hundreds of the nearest and brightest AGN at higher X-ray energies, with far less bias, while reaching luminosities comparable to those of deep Chandra and XMM surveys. In this study, high quality X-ray (0.5-200 keV) spectra of 617 non-blazar AGN from the Swift-BAT AGN Spectroscopic Survey (BASS) provide a low-redshift template for simulations of deeper (z ~ 1-2) Chandra spectra that vary in both luminosity and obscuration. We present quantitative results on the selection effects of the Chandra COSMOS Legacy Survey and Chandra Deep Field-South. We also present an analysis of simulated spectra for AXIS, the NASA’s upcoming high resolution X-ray probe mission. Thus, this study aims to both deepen our understanding of existing data and prepare us to optimally benefit from future missions.