Authors: David Izquierdo-Villalba, Melanie Habouzit, Matteo Bonetti, Silvia Bonoli, Alessia Gualandris, Marta Volonteri, Federico Angeloni, Enrico Barausse, Aklant. K. Bhowmick, Laura Blecha, Alexander Bonilla, Elisa Bortolas, Mesut Çalışkan, Pedro R. Capelo, Ana Caramete, Laurentiu Caramete, Nianyi Chen, Monica Colpi, Thierry Contini, Romeel Davé, Pratika Dayal, Colin DeGraf, Roger Deane, Roberto Decarli , Rémi Delpech, Tiziana Di Matteo, Chin An Dong-Páez, Alister W. Graham, Daryl Haggard, Dimitrios Irodotou, Peter H. Johansson, Atte Keitaanranta, Luke Kelley, Fezzel Mahmood Khan, Vivienne Langen, Kunyang Li, Shihong Liao, Alberto Mangiagli, Sylvain Marsat, Joe McCaffrey, Yueying Ni, Coral Pillay, Florentina-Crenguta Pislan, Alexander Rawlings, John A. Regan, Bastián Reinoso, Jaelyn S. Roth, Milton Ruiz, Olga Sergijenko, Alberto Sesana, Golam.M. Shaifullah, Jasbir Singh, Daniele Spinoso, Alexandre Toubiana, Michael Tremmel, Alessandro Trinca, Rosa Valiante, Yihao Zhou, Yohan Dubois, Luca Graziani, Christopher C. Lovell, Sebastien Peirani, Will Roper, Joop Schaye, Raffaella Schneider, Maxime Trebitsch, Aswin. P. Vijayan, Mark Vogelsberger, Stephen. M. Wilkins, John H. Wise
In the hierarchical paradigm of galaxy formation, central massive black holes (MBHs) are expected to coalesce after the merger of their host galaxies. One of the main goals of the Laser Interferometer Space Antenna (LISA) is to constrain the origin and growth of MBHs through their merger rates and mass distribution. Predicting MBH merger rates requires not only tracing their statistical population from large to small physical scales (kpc to sub-pc) but also modelling their formation, accretion, dynamics, mergers, and their galactic physical processes across cosmic time. This project is the result of a large collaborative effort undertaken by the LISA Astrophysics Working Group, bringing together its collective expertise on MBH formation, evolution, and modelling, to build a comprehensive understanding of MBH merger rates across cosmic time. The project compares various theoretical predictions of MBH merger rates, quantifies the spread, and evaluates the global astrophysical uncertainties of the LISA event rates. To build a unique and complete view, our work is based on about 20 semi-analytical models and cosmological simulations from the literature, all employing distinct approaches to modelling MBH and galaxy physics. To compute the merger rates, we also incorporate delays arising from the dynamical phase of MBH hardening to coalescence. We present the expected LISA merger rates given current galaxy formation models and discuss how the merger rate depends on model assumptions, such as the seeding model and the resolution of cosmological simulations.