What Are the Pillars of Reionization? Revising the AGN Luminosity Function at z ∼ 5

Abstract

In the past, high- z active galactic nuclei (AGNs) were given a minor role as possible drivers of reionization, despite initial evidence in favor of their large space densities at low luminosities by Chandra and the Hubble Space Telescope. Recent observations from JWST are finding relatively large numbers of faint AGNs at z > 4, convincingly confirming these early results. We present a sample of z ∼ 5 AGNs, both from wide, shallow ground-based surveys and from deep, pencil-beam observations from JWST, allowing us to estimate their space densities with unprecedented accuracy. The bright end ( M 1450 6, well into the Epoch of Reionization. This is an important indication that high- z AGNs could be major contributors to the reionization of the Universe.