The Co-Evolution of Galaxies and Black Holes: Current Status and Future Prospects

TL;DR

This paper reviews the current understanding of the co-evolution of galaxies and supermassive black holes, highlighting recent findings at low redshift and prospects for future high-redshift observations with advanced telescopes.

Contribution

It synthesizes recent observational evidence and discusses future observational strategies to better understand galaxy-black hole co-evolution across cosmic time.

Findings

Black holes grow mainly in less massive early-type galaxies at low redshift.

Black hole growth is statistically linked to star formation in galaxy centers.

Future telescopes will enable detailed studies of galaxy and black hole formation at high redshift.

Abstract

I begin by summarizing the evidence that there is a close relationship between the evolution of galaxies and supermassive black holes. They evidently share a common fuel source, and feedback from the black hole may be needed to suppress over-cooling in massive galaxies. I then review what we know about the co-evolution of galaxies and black holes in the modern universe (z < 1). We now have a good documentation of which black holes are growing (the lower mass ones), where they are growing (in the less massive early-type galaxies), and how this growth is related in a statistical sense to star formation in the central region of the galaxy. The opportunity in the next decade will be to use the new observatories to undertake ambitious programs of 3-D imaging spectroscopy of the stars and gas in order to understand the actual astrophysical processes that produce the demographics we observe. At high redshift (z > 2) the most massive black holes and the progenitors of the most massive galaxies are forming. Here, we currently have a tantalizing but fragmented view of their co-evolution. In the next decade the huge increase in sensitivity and discovery power of our observatories will enable us to analyze the large, complete samples we need to achieve robust and clear results.