Dynamical Formation of Black Hole Mergers

Gravitational wave (GW) astrophysics is bound to have an exceptional future building on the success of LIGO/Virgo and propelled by the next generation of ground-based detectors (expected to see hundreds-of-thousands of GW sources per year) and space-borne observatories, such as LISA and DECIGO (that will make multi-band GW astrophysics a reality). This ERC research program will lead to new ideas and tools to probe in unprecedented ways the origin of binary black hole (BBH) mergers, with particular focus on constraining the dynamical formation of GW sources. I will address the outstanding question of how BBHs form and merge in our Universe by providing the GW community with: (1) - The first and largest public BH scattering data-base, with BBH merger probabilities and GW observables derived from general-relativistic few-body interactions, thought to dominate BBH assembly in environments from globular clusters to Active-Galactic-Nuclei disks. This initiative fills out a major gap and will ensure a consistent progress in this field. (2) – A new method for modeling the formation of BBHs in dense stellar clusters throughout cosmic time. It will be based on a new hybrid approach that evolves BBHs on top of a stellar background that is evolved using statistical mechanics. Combined with our BH scattering database, this framework will be the fastest and most accurate way of modeling BBH mergers in stellar clusters. (3) - A new way of directly observing the formation of eccentric GW mergers in three-body scatterings through GW phase-shifts measurements, caused by tidal-forces and time-delay effects from the third body. This idea opens up for the possibility of probing the origin of individual BBH mergers using LIGO/Virgo and future detectors. We will be the first group to present a new search strategy for quantifying what can be learned about each individual triple system and its astrophysical environment.