Cosmic X-ray Surveys of Distant Active Galaxies: The Demographics, Physics, and Ecology of Growing Supermassive Black Holes

TL;DR

This review summarizes 15 years of cosmic X-ray surveys of active galactic nuclei, highlighting advances in understanding supermassive black hole growth, AGN demographics, physics, and environmental interactions, and discussing future research directions.

Contribution

It provides a comprehensive overview of the progress made in AGN studies through X-ray surveys, emphasizing the roles of key missions and multiwavelength data.

Findings

Improved understanding of AGN demographics and evolution.

Insights into physical processes in AGNs.

Identification of key unresolved questions and future prospects.

Abstract

We review results from cosmic X-ray surveys of active galactic nuclei (AGNs) over the past ~ 15 yr that have dramatically improved our understanding of growing supermassive black holes in the distant universe. First, we discuss the utility of such surveys for AGN investigations and the capabilities of the missions making these surveys, emphasizing Chandra, XMM-Newton, and NuSTAR. Second, we briefly describe the main cosmic X-ray surveys, the essential roles of complementary multiwavelength data, and how AGNs are selected from these surveys. We then review key results from these surveys on the AGN population and its evolution ("demographics"), the physical processes operating in AGNs ("physics"), and the interactions between AGNs and their environments ("ecology"). We conclude by describing some significant unresolved questions and prospects for advancing the field.