Abstract

Coalescing massive black hole binaries are key targets for several ongoing and planned gravitational wave facilities, such as Pulsar Timing Arrays and the LISA mission. These observatories promise to probe the properties of merging massive black holes across the evolution of our Universe, unveiling the clustering and growth of massive black holes and their host galaxies all the way up to the cosmic dawn. In this seminar, I will describe the new advances and challenges in the modelling of the path to coalescence of massive black hole binaries. I will especially focus on recent results that challenge the traditional paradigm of binary evolution, from the large-scale galaxy merger down to the small separations at which the evolution is dominated by stellar hardening, interactions with a gaseous disk and, finally, gravitational-wave emission. I will conclude by discussing the critical importance of constructing realistic models for the galaxy hosts of massive binaries to properly assess the detection prospects of upcoming gravitational-wave detectors.