Binary black hole mergers: formation and populations

TL;DR

This paper reviews the physical processes leading to the formation and merger of stellar binary black holes, focusing on isolated binary evolution and dynamical formation in star clusters, highlighting key uncertainties and observable signatures.

Contribution

It provides a comprehensive overview of the formation channels of binary black holes, emphasizing the physical uncertainties and observational imprints of each channel.

Findings

Dynamical formation influences BBH mass, spin, and orbital properties.

Uncertainties in supernova physics and common envelope evolution affect formation predictions.

Dynamical encounters in star clusters can produce distinctive BBH signatures.

Abstract

We review the main physical processes that lead to the formation of stellar binary black holes (BBHs) and to their merger. BBHs can form from the isolated evolution of massive binary stars. The physics of core-collapse supernovae and the process of common envelope are two of the main sources of uncertainty about this formation channel. Alternatively, two black holes can form a binary by dynamical encounters in a dense star cluster. The dynamical formation channel leaves several imprints on the mass, spin and orbital properties of BBHs.