Towards the Multi-Messenger View of Our Universe

In this talk, I will review the state-of-the-art in our theoretical efforts to understand the physics governing the evolution of the supermassive black hole population across cosmic time. I will discuss the complex interplay between galaxies and supermassive black holes in the early Universe, from the formation of dwarf galaxies that may host the elusive intermediate mass black holes, to the most massive proto-clusters harbouring 'gargantuan' black holes. I will emphasize what we can learn from the latest cosmological simulations of these objects, in conjunction with the incoming JWST data.

I will then describe our efforts to understand supermassive black hole merger rates from cosmological simulations, and what these can reveal when combined with the Pulsar Timing Array findings. Finally, I will discuss the synergies between JWST and other upcoming space missions, such as Athena and LISA, focusing on black hole binaries on small scales, which will ultimately unlock the multi-messenger view of our Universe.