Black hole demography at the dawn of gravitational-wave astronomy: state of the art and future perspectives

TL;DR

This paper reviews the current understanding of black hole populations in the era of gravitational-wave astronomy, emphasizing the importance of future measurements of black hole properties to constrain their formation channels and astrophysical processes.

Contribution

It provides a comprehensive overview of black hole demography, discusses formation scenarios, and highlights future perspectives for gravitational-wave observations.

Findings

Detection of massive black holes with 30-40 solar masses.

Formation channels remain poorly constrained.

Future measurements will clarify black hole origins.

Abstract

The first LIGO-Virgo detections have confirmed the existence of massive black holes (BHs), with mass $30-40$ M$_\odot$. Such BHs might originate from massive metal-poor stars ($Z<0.3$ Z$_\odot$) or from gravitational instabilities in the early Universe. The formation channels of merging BHs are still poorly constrained. The measure of mass, spin and redshift distribution of merging BHs will give us fundamental clues to distinguish between different models. Also, a better understanding of several astrophysical processes (e.g. common envelope, core-collapse supernovae, and dynamical evolution of BHs) is decisive, to shed light on the formation channels of merging BHs.