Massive black hole binaries: dynamical evolution and observational signatures

TL;DR

This paper reviews the current understanding of the dynamical evolution of massive black hole binaries during galaxy mergers, discussing formation timescales, observational signatures, and uncertainties affecting detection prospects.

Contribution

It provides a comprehensive overview of recent theoretical developments, open issues, and candidate observations related to massive black hole binaries in galaxy mergers.

Findings

Uncertain formation and coalescence timescales impact detection rates.

Recent developments improve understanding of black hole pairing.

Candidates for massive black hole binaries have been identified in observations.

Abstract

The study of the dynamical evolution of massive black hole pairs in mergers is crucial in the context of a hierarchical galaxy formation scenario. The timescales for the formation and the coalescence of black hole binaries are still poorly constrained, resulting in large uncertainties in the expected rate of massive black hole binaries detectable in the electromagnetic and gravitational wave spectra. Here we review the current theoretical understanding of the black hole pairing in galaxy mergers, with a particular attention to recent developments and open issues. We conclude with a review of the expected observational signatures of massive binaries, and of the candidates discussed in literature to date.