Exploring AGN Activity over Cosmic Time with the SKA

TL;DR

This paper discusses planned wide and deep SKA radio surveys to study the evolution of active galactic nuclei (AGN) activity across cosmic time, including the early universe, by detecting faint radio sources.

Contribution

It introduces specific SKA survey strategies capable of detecting faint radio AGN up to high redshifts, enabling unprecedented studies of AGN evolution.

Findings

Detection of radio-loud and radio-quiet AGN down to low luminosities at high redshifts.

First-time detailed study of AGN activity evolution from the cosmic dawn.

Coverage of all environmental densities in AGN evolution studies.

Abstract

In this Chapter we present the motivation for undertaking both a wide and deep survey with the SKA in the context of studying AGN activity across cosmic time. With an rms down to 1 $\mu$Jy/beam at 1 GHz over 1,000 - 5,000 deg$^2$ in 1 year (wide tier band 1/2) and an rms down to 200 nJy/beam over 10 - 30 deg$^2$ in 2000 hours (deep tier band 1/2), these surveys will directly detect faint radio-loud and radio-quiet AGN (down to a 1 GHz radio luminosity of about $2\times10^{23}$ W/Hz at $z=6$). For the first time, this will enable us to conduct detailed studies of the cosmic evolution of radio AGN activity to the cosmic dawn ($z\gtrsim6$), covering all environmental densities.