Joint seminar organized by APC (University of Paris) and Service de Physique Théorique (ULB, Brussels)

In this talk I will show how to derive analytical gravitational waveforms associated to the coalescence of a "hairy" black hole binary in Einstein-scalar-Gauss-Bonnet gravity (ESGB). I will present the post-Newtonian (PN) Lagrangian and gravitational wave fluxes associated to such systems. The PN framework relies on reducing the black holes to point particles with scalar field-dependent masses. In light of the first law of thermodynamics of ESGB black holes, I will show that this procedure amounts to fixing the Wald entropy of each black hole during their slow, adiabatic inspiral. An notable consequence is that inspiraling ESGB black holes might slowly grow scalar "hair" until they turn into naked singularities. I will then extend the scope of the PN approximation to the strong field regime near merger by generalizing the Effective-One-Body (EOB) formalism to ESGB gravity.