Observations of Early Black Holes Before and After JWST

TL;DR

This paper reviews the evolution of understanding about early supermassive black holes, highlighting how JWST observations are revolutionizing the field by providing new insights into black hole growth and host galaxy environments in the early universe.

Contribution

It provides a comprehensive overview of the progress in observing early black holes, emphasizing the transformative impact of JWST data on the field.

Findings

JWST enables precise black hole mass measurements.

JWST reveals detailed host galaxy properties at high redshift.

New environmental studies of early black holes are emerging.

Abstract

These notes are from three lectures given at the 54th Saas-Fee Advanced Course of the Swiss Society of Astrophysics and Astronomy in January 2025. This chapter reviews the dramatic evolution in our understanding of supermassive black holes in the first billion years, from ground-based discoveries to recent space-based infrared observations with JWST. Section 1 introduces AGN and quasars to contextualise observations at the highest redshifts. Section 2 reviews the pre-JWST understanding of early quasars, including personal accounts of how key discoveries were made. Section 3 examines how JWST is transforming the field, from black hole mass measurements and host galaxy characterisation to large-scale environmental studies, and identifies emerging directions.