The Formation of the First Massive Black Holes

TL;DR

This paper reviews the origins of supermassive black holes, comparing growth via accretion and mergers with direct gas collapse, and discusses future observational strategies to distinguish these models.

Contribution

It provides a comprehensive comparison of the main theories for SMBH formation and outlines how upcoming observations can test these scenarios.

Findings

Supermassive black holes can form via accretion and mergers or direct collapse.

Future telescopes like JWST and (e)LISA can help distinguish formation models.

The chapter discusses alternative and exotic SMBH formation ideas.

Abstract

Supermassive black holes (SMBHs) are common in local galactic nuclei, and SMBHs as massive as several billion solar masses already exist at redshift z=6. These earliest SMBHs may grow by the combination of radiation-pressure-limited accretion and mergers of stellar-mass seed BHs, left behind by the first generation of metal-free stars, or may be formed by more rapid direct collapse of gas in rare special environments where dense gas can accumulate without first fragmenting into stars. This chapter offers a review of these two competing scenarios, as well as some more exotic alternative ideas. It also briefly discusses how the different models may be distinguished in the future by observations with JWST, (e)LISA and other instruments.