The Hot and Energetic Universe: The formation and growth of the earliest supermassive black holes

Understand

A crucial challenge in astrophysics over the coming decades will be to understand the origins of supermassive black holes (SMBHs) that lie at the centres of most, if not all, galaxies.

• The processes responsible for the initial formation of these SMBHs and their early growth via accretion - when they are seen as Active Galactic Nuclei (AGN) - remain unknown.
• To address this challenge, we must identify low luminosity and obscured z>6 AGNs, which represent the bulk of early SMBH growth.
• Sensitive X-ray observations are a unique signpost of accretion activity, uncontaminated by star formation processes, which prevent reliable AGN identification at other wavelengths (e.g.